Learn how to make a classic vinaigrette and you'll never buy a bottle of it again. Keep it in a screw-topped jar in the fridge, then you can just shake and serve. Mix together a clove of crushed garlic with 1tsp sea salt. Add 1tbsp Dijon mustard and 1tbsp white or red wine vinegar. Mix well, add freshly ground black pepper, then whisk in 6tbsp olive oil.