How do I make a salad dressing?

A vinaigrette is an emulsion of oil and acid that naturally wants to separate. Mustard contains compounds that hold the two together, which is why almost every classic dressing includes it. Once you have the ratio, everything else is substitution.

What you'll need

• Oil
• Vinegar or lemon juice
• Mustard
• Salt and pepper
• Jar with a lid or a small whisk

Step by step

1. Start with three parts oil to one part acid.Three tablespoons of oil to one of vinegar makes enough for a large salad. Adjust to taste — some prefer 2:1 for a sharper dressing.
2. Put the acid, mustard, salt and pepper in a jar first.Salt dissolves in the acid. It won't dissolve properly once the oil is in.
3. Add about a teaspoon of mustard per three tablespoons of oil.Dijon is the default. This is the emulsifier — without it the dressing separates almost immediately.
4. Add the oil, put the lid on, and shake hard for 20 seconds.Or whisk while pouring the oil in slowly. Both work; the jar is easier and makes less washing up.
5. Taste and adjust — usually more salt or more acid.Taste it on a leaf rather than off a spoon. Undiluted dressing always tastes sharper than it will on the salad.
6. Dress the salad immediately before serving, and use less than you think.Leaves should be lightly coated, not swimming. Dressed salad wilts within minutes.
7. Store leftovers in the fridge and shake again before use.It keeps about a week. It will separate — that's normal, and shaking brings it back.

Tips

• Vary the acid: red wine vinegar, sherry vinegar, cider vinegar, lemon juice — each gives a different character from the same technique.
• A little honey or maple syrup balances a very sharp vinegar and helps the dressing cling.
• Add a crushed garlic clove or a finely chopped shallot to the acid and leave it 10 minutes before adding the oil — the acid softens the raw bite.
• Make a large jar and keep it in the fridge. Having dressing ready is the difference between eating salad and not.

Common mistakes

• Leaving out the mustard — Without an emulsifier the dressing separates within a minute and coats unevenly.
• Adding salt after the oil — It won't dissolve in oil, so you get gritty dressing and uneven seasoning.
• Over-dressing the salad — Leaves should be lightly coated. Too much makes everything heavy and soggy.
• Dressing well before serving — Acid and salt wilt leaves quickly. Dress at the table.

Questions people ask