If your approach to cooking vegetables is to throw them into a pot – or spread out on a roasting tray – and hope for the best, then chances are you're not getting the best possible results. Neither overcooked nor undercooked veggies bring much to a meal – and, as all vegetables respond differently to different ways of cooking, getting them right each time can be tricky. To help you on your way to fluffy, golden roast potatoes, tender (and not waterlogged) broccoli and slime-free mushrooms, we've put together the ultimate list of vegetable dos and don'ts.

Have you been cooking vegetables wrong your whole life? Click or scroll through our top tips to discover what NOT to do, and how to get it right, every time.

Asparagus is expensive, so it should always be treated with respect. Firstly, choose your asparagus carefully; too thin, and you'll run the risk of overcooking it – but too thick, and it'll be too woody and fibrous. Peeling your asparagus is another common mistake. It's pointless, and will leave you with sad, thin little stalks.

For the tastiest asparagus ever, snap off the ends of the spears, trim them with a knife to neaten up the edges, then steam for up to five minutes, depending on the size of your spears (test them with a skewer to make sure they're perfectly tender). For a lip-smacking starter or light meal, serve with Hollandaise sauce – or with melted butter, lemon and a sprinkle of Parmesan. Firing up the barbecue? Toss your asparagus in oil and seasoning, then grill for a few minutes.

Broccoli can go from a vibrant veggie with a hint of crunch to a grey-green gloop in a matter of minutes, losing valuable nutrients along the way. Chopping the florets too small is a major culprit, loosening the tiny buds (the little green bits) and resulting in a mushy mess, with much of the broccoli left behind in the cooking water. Another issue is boiling them to within an inch of their life.

Instead, chop them into even-sized pieces, then steam for a few minutes. If you're preparing your broccoli ahead, run it under cold water in a colander to halt the cooking process halfway through. Cooked broccoli partners perfectly with a squeeze of lemon, a knob of butter or a heap of grated cheese. Broccoli is also lovely in a stir-fry, and it roasts well, too; simply toss it in oil and seasoning, then pop it into a hot oven for 25 minutes.

These much-maligned, often-overcooked veggies don't deserve all the bad publicity they get. And they certainly don't deserve being boiled into oblivion. Don't bother cutting a cross in the base of each sprout before cooking – it'll only make them soggy. They're more versatile than you may think, and will taste much better steamed or roasted, helping to retain their flavour and texture.

Look for small, vibrantly green sprouts (if you can find them on the stalk, they'll keep much better) and remove any tired-looking outer leaves. Allow five to eight minutes for your sprouts to steam, depending on their size. Undercooked sprouts are as uninspiring as overcooked ones, so use a skewer to check they're done, then serve with plenty of butter and black pepper. For an even more flavoursome side dish, pop your steamed sprouts into a hot frying pan with oil and butter, tossing them around so they brown at the edges. For the final flourish, add some crisp smoked bacon to serve.

Often overcooked, soggy and under-seasoned, cabbage's reputation has suffered over the years, but it can be incredibly tasty. Choosing the wrong cabbage in the first place is often the first mistake – it needs to be so fresh that the leaves squeak as you remove the core. Cutting it too roughly, and into big strips, means it's less likely to cook evenly, too, while another common error is simply not draining boiled cabbage sufficiently. Once emptied into a colander, it's best to push the cooked cabbage down with a saucer or small plate, pressing to remove as much water as possible.

The best way is to shred the cabbage finely, pack it into a saucepan with some sea salt, pour over some boiling water, and leave on a high heat for a few minutes. Much as we love a bowl of buttery cabbage with lots of black pepper, this leafy green is more versatile than you may think. You could add it to a stir-fry, or hop on the latest trend by roasting or chargrilling it. To roast it, cut it into wedges, then rub in some oil and seasoning before putting it in the oven for around 25 minutes on a high heat. To chargrill, prepare it in the same way, and turn each wedge a few times until darkened and tender. 

It's pretty hard to overcook an onion, but undercooked onions are never a good thing. The cooking process brings out an onion's natural sweetness as it begins to caramelise, so don't try to cut corners here! For a perfectly tender, meltingly soft result, chop or slice your onions as evenly as possible, and cook them in a frying pan for at least 20 minutes.

Really good caramelised onions can take up to 45 minutes, depending on the quantity, but they're so worth the time. Adding a pinch of salt will help your onions to cook more quickly, and will also prevent them from burning. For even more flavour, add a sprig of fresh thyme or a bay leaf. For extra sweetness, throw in a pinch of sugar. 

Carrots a bit on the bendy side? That means they aren't fresh; a good carrot should be firm and blemish-free. Though it's commonly done, summer carrots don't actually need peeling – just give them a quick wash, trim them (leaving the tops of the stalks intact), then steam for five to seven minutes until just tender. Winter carrots are fatter and less sweet, with a slightly woody taste, and it's easy to get the cooking wrong, resulting in sad, soggy slices or chunks so tough, your teeth are at risk.

Here's our fail-safe recipe for perfect winter carrots: peel them, cook them in salted boiling water (enough to just about cover them) for around 20 minutes, then toss them in butter and black pepper to serve. Roasted summer or baby carrots also make a great dish. Just coat them in oil, add a little salt and pepper, drizzle with honey, and roast in a hot oven for around 20 minutes. You could do the same with winter carrots too; simply cut them into chunks and steam for five minutes before roasting. Adding a little spice, such as cumin, will take the flavour up a notch.

When boiled, cauliflower absorbs a large amount of water and becomes soggy. It's often overcooked, too, resulting in a mushy mess that's anything but appetising. For perfect cauliflower, steaming is the way to go: cut it up into equal sized florets, then put them into the steamer basket stalk-side down, to prevent them from overcooking. Steam them for around six minutes, until the stalks are just tender.

With the recent rise of plant-based eating, cauliflower has seen a resurgence – and these days, it can be cooked in many different ways (though we still love a good old-fashioned bowl of cauliflower cheese). When roasted, it's no longer just a side, but a dish in its own right: toss it in oil and seasoning – you could add some of your favourite spices – then cook it in a hot oven for around 10 minutes, depending on its size. 

Courgettes are delicate vegetables, without a great deal of flavour of their own. They have a high water content, so beware of steaming or boiling them – it'll render them dull and tasteless. When it comes to choosing your courgettes, it's a case of the smaller, the better; courgettes are baby marrows, so the larger they become, the more watery they'll be. The ideal courgettes should be firm, with no blemishes.

Make your courgettes shine by roasting, frying, chargrilling or grilling them. If they're small, halve them lengthways (and, if they're on the larger side, cut them into chunks), then toss them in olive oil with plenty of seasoning. However you plan to cook them, make sure you do it over a high heat, or they may become soggy. Looking for a light lunchtime option? Courgettes also make a lovely raw salad – just slice them into ribbons with a swivel peeler, then toss them in a herby vinaigrette.

When cooked incorrectly, kale can taste chewy and bitter. Do it the right way, however, and it can be a brilliantly flavoursome side dish. Firstly, try to buy leaves that are on the smaller side, and don't leave them in the fridge for days – the longer it's kept, the more bitter kale gets. Remove any woody stalks before chopping the leaves into bite-sized pieces. To get rid of any grit, put your kale into a large bowl of cold water and swish it around, so the grit sinks to the bottom. Instead of draining, lift the leaves from the surface, then place them in a colander. 

Kale can be steamed, stir-fried or roasted – but first, massage the leaves with a little oil, in order to break down the fibres. To roast it, add a sprinkle of sea salt and a spice of your choice, pop it on a baking tray in the oven on a medium-low heat, and cook for around 15 minutes. Prefer to steam your kale? It'll need plenty of olive oil (or butter) and seasoning to bring out its flavour.

Surprisingly, potato mashers do not make perfect mashed potatoes; more often than not, if you use this tool, you'll end up with a gluey, lumpy result. Food processors aren't your friend here, either (they may get rid of the lumps, but your mash will be equally gooey). So, what should you use, exactly? For fluffy, delicious mashed potatoes, we recommend using a potato ricer or a food mill – a gadget that mashes and sieves soft food via a crank-turned mechanism.

Steaming your potatoes before mashing them will help to keep them dry, resulting in perfect mash. Alternatively, boil them in salted water – with the water just about covering the spuds – then leave them to steam for a few minutes in a colander. Next, stir in a good glug of warm milk, some melted butter and some sea salt. A little grated cheese and fresh herbs won't go amiss, either. Don't worry if you make too much; leftover mashed potatoes are ideal for making fish cakes and vegetable fritters, or throwing into a breakfast hash.

Mushrooms should never be washed; they already contain a lot of moisture, and washing them will mean that they absorb even more. This is probably why some people find mushrooms too slimy. To prepare them before cooking, simply wipe away any dirt with a kitchen towel – and don't peel them, as the peel contains flavour. Trim the stalks if necessary, but don't discard them.

Mushrooms add a savoury umami taste to so many dishes, from soups and stews to simple slices of toast. To cook the perfect mushrooms, you'll need a high heat, which will help get rid of excess moisture. Add butter and oil to a large frying pan, heat for a few minutes, then toss in your mushrooms, along with a little sea salt. Turn up the heat to high and cook for around 10 minutes, stirring constantly, until the mushrooms have coloured, and any liquid has evaporated.

Okra only becomes slimy if it's cut, then cooked in water – so, if you plan on adding it to a dish, fry it first. That way, the sticky liquid that comes from the seeds will actually help to thicken your sauce (perfect for a Cajun gumbo or curry). Your raw okra must be bright green, and perfectly firm, with no blemishes. Be sure to trim off the ends before slicing it up.

The best way to convert okra haters into okra enthusiasts? Try frying, deep-frying, chargrilling or barbecuing it. Whichever method you choose, toss it in oil with plenty of seasoning and garlic powder before cooking (it should take around five minutes). It's also delicious dipped into a cornmeal or tempura batter, then deep-fried until crispy.

Contrary to popular belief, fresh peas should never be cooked in water; this way, they'll lose both flavour and nutrients. Instead, young peas should be steamed for no more than two minutes. Bigger, late season peas can have quite a different flavour, so be sure to steam them for longer (a few minutes should do it). As for frozen peas (a must-have staple, if you ask us), one of the most common mistakes is just to throw them straight into boiling water. They can end up a bit dry and crinkly.

The best way to cook frozen peas is to thaw them in a pan for around half an hour, then simply add a knob of butter (no extra water required) and cook over a high heat, stirring until heated through. To serve, try mashing them up and spreading on toasted sourdough with crumbled feta cheese. You could also make a speedy soup with peas, thawed or even straight from the freezer, and a little vegetable stock, adding some crisp bacon (if you like) to serve. Peas are also brilliant in a midweek risotto; add them once the rice is cooked, with a large knob of butter and a sprinkle of freshly grated Parmesan.

The secret to the perfect roast potato? You'll need a floury potato, not a waxy one. You may have heard that you should boil your potatoes before roasting them, but this is a myth – water is the enemy of crispiness, so it's best to steam them instead. Once steamed, don't simply bundle them into the oven; leave them to stand, covered with a cloth, for a few minutes to ensure any excess water has evaporated.

The ultimate goal is a crisp exterior with a soft, fluffy centre. Once your potatoes have rested, give them a shake in a colander to roughen up the edges, then season them well with sea salt. Next, you'll need to ensure that the hot potatoes go into hot fat, so make sure your sunflower oil or duck fat is piping hot in the oven tray. Top tip: your roast potatoes will keep well for a few hours in the tray, so if you're short on oven space, you can reheat them before serving.

These leafy greens have a high water content and shrink to almost nothing when cooked, so underestimating how much you'll need is a common error. Another is boiling it. In fact, the only time your spinach should even see water is when you're washing it. Fresh spinach can be a bit dusty, muddy and gritty, so be sure to cut off any tough stalks and remove any brown leaves first. Then, fill your sink with cold water, put the spinach in and swirl it around a few times – any grit should sink to the bottom. Scoop the washed spinach into a colander, and allow it to drain well. 

Firstly, make sure you cook enough! A couple of generous handfuls per person is a good amount if you're serving it as a side dish. Melt a knob of butter in pan, add your spinach and a good grinding of sea salt, then cover with a lid. Leave for a couple of minutes, shaking the pan a few times. You could also try it with pasta, blue cheese and toasted walnuts; simply add your spinach to your cooked, drained pasta, and the heat will wilt the spinach for you.

Now read our top dos and don'ts for other common foods (and discover what you've been doing wrong)