Ingredient

Dijon mustard

Dijon is the mustard to keep if you keep only one. It is sharp without being crude, smooth enough to disappear into a sauce, and — the part most people never think about — it is an emulsifier, which is why a vinaigrette made with it stays together and one made without it separates on the plate.

What makes it Dijon

Two things: brown mustard seed rather than yellow, and verjuice, wine or a mild acid rather than the harsh vinegar used in many other mustards. The seed gives it a sharper, more pungent heat than a mild yellow mustard; the gentler acid lets that heat come through cleanly rather than being buried under sourness.

The name is not protected in the way a PDO cheese is. Dijon mustard can be made anywhere, and a great deal of it is — including most of what is sold in Britain. The style is what the word describes.

Compared with English mustard, which is a blend of brown and yellow seed mixed to be as fiercely hot as possible, Dijon is more aromatic and less punishing. Compared with American yellow mustard, which is mild yellow seed with turmeric and vinegar, it is in a different league of intensity.

The emulsifier, and why it matters

Oil and vinegar do not mix. Shake them and they combine briefly, then separate — the oil droplets find each other and coalesce, and within a minute you have two layers again.

Mustard prevents that. It contains mucilage from the seed coat and proteins that position themselves at the boundary between oil and water, coating each droplet and stopping the droplets merging. That is what an emulsifier does, and it is the same job egg yolk does in mayonnaise.

So a teaspoon of Dijon in a vinaigrette is not only a flavour decision. It is the structural component, and a dressing made without it will split in the bowl while you are still tossing the salad. The classic proportion — three parts oil to one of vinegar, with mustard and salt — works because all four parts have a job.

It is also why mustard turns up in cheese sauces, in pan sauces and in salad creams: wherever fat and liquid have to stay together.

Where to use it

• In every vinaigrette. Whisk the mustard with the vinegar and salt first, then add the oil slowly. Emulsifying before the oil arrives works far better than adding everything at once.
• In a cheese sauce or macaroni cheese, half a teaspoon, where it sharpens the dairy without being identifiable as mustard.
• On meat before roasting — pork, lamb, beef — as a coating that both seasons and helps a herb or breadcrumb crust stick.
• In a pan sauce, whisked in off the heat at the end. Boiling it drives off the pungency.
• In mayonnaise, where it reinforces the egg yolk and adds sharpness.
• With cheese, ham, sausages and in a sandwich, which is what most jars are actually used for.
• In a marinade, where its acid and its emulsifying action both help.
• Late rather than early. The compounds that make mustard pungent are volatile and heat degrades them, so mustard cooked for an hour contributes body but little heat.

The mustards, and when to use which

Dijon

Smooth, sharp, aromatic. The default for dressings, sauces and cooking. The most useful jar.

Wholegrain

Seeds left partly whole in a vinegar and wine base. Texture and mild heat. For serving alongside food rather than dissolving into it.

English

Very hot, made from powder or as a paste. For beef, ham and cheese, in small quantities. Its heat fades quickly once mixed.

American yellow

Mild, vinegary, coloured with turmeric. For hot dogs and burgers, where mildness is the point.

Honey mustard and flavoured mustards

Sweetened or spiced blends. Fine as condiments, and their sugar can burn in a hot pan.

Dijon substitute

Wholegrain will emulsify a dressing almost as well. English mustard works in a fraction of the quantity. Mustard powder mixed with a little water does the job.

Common questions