Vinaigrette

A vinaigrette is a simple sauce of oil and an acid, usually vinegar or lemon juice, seasoned with salt and often mustard. It is the most common salad dressing and is also spooned over vegetables, grains, beans, fish and grilled meat. The classic ratio is 3 parts oil to 1 part acid.

How to do it

For about 120 ml (1/2 cup):

1. In a bowl or jar, mix 2 tablespoons of vinegar or lemon juice with a pinch of salt until it dissolves.
2. Add 1 teaspoon of Dijon mustard and a finely chopped shallot if you like. Let the shallot sit in the vinegar for 5 to 10 minutes to soften.
3. Whisk in 6 tablespoons of olive oil in a slow stream, or put a lid on the jar and shake hard.
4. Taste on a leaf of the salad and adjust the salt and acid.

Why it works

Oil and vinegar do not stay mixed. Whisking breaks the oil into tiny drops, forming a temporary emulsion. Mustard contains compounds that coat the drops and slow them from joining up again, so the dressing stays thick and creamy for longer. Salt dissolves in vinegar but not in oil, which is why it goes in first.

How to use it

Try different oils and acids: walnut oil with sherry vinegar, olive oil with lemon, or balsamic vinegar with a drop of honey. For soft lettuce, dress just before serving. Warm potatoes, lentils and beans soak up dressing best when they are still warm.

How to store it

A plain oil, vinegar and mustard vinaigrette keeps in a jar in the fridge for up to 2 weeks. With fresh garlic, shallot or herbs, use it within 3 to 4 days. Olive oil may set when cold; let it warm up and shake again.

Common mistakes

• Dressing greens too early, so they wilt.
• Using wet leaves, which push the dressing off. Dry them well.
• Adding salt after the oil, so it does not dissolve.
• Sticking to 3 to 1 when the acid is mild or sharp. Taste and adjust.

In recipes

In the US, "French dressing" can also mean a sweet, orange, tomato-based bottled dressing, which is a different thing.