Fresh English hot mustard

Heat that is made in the bowl

English mustard mixed from powder is the plainest mustard there is: finely ground seed, cool water and a few minutes' patience. Nothing in the tin is hot yet. Mustard seed carries sulphur-containing compounds called glucosinolates and, separately, an enzyme called myrosinase. While the seed is dry and whole the two stay apart; once its cells are broken and wetted, the enzyme converts the glucosinolates into isothiocyanates, the pungent compounds that give mustard its bite. Milling has already done the breaking, and the water you stir in does the rest. That is why a freshly mixed paste can feel fierce in the nose without tasting sour: its heat comes from chemistry started in the bowl, not from vinegar.

The formula keeps everything that might interfere out of the way. It uses water alone, cool rather than hot, and no acid. Heat is the clearest risk to fresh pungency: when myrosinase was extracted from black, brown and yellow mustard seed and tested in the laboratory, the three enzymes differed in how well they withstood heating, which helps explain why cooked and cold-mixed mustards made from similar seed behave so differently. Leaving vinegar out is this formula's own choice, on the reasoning that water should reach the powder first; anything sharper belongs to the prepared-style variation.

The rest after mixing is a flavour step, and its length belongs to the powder. Colman's foodservice instructions call for cold water and ten minutes, the figure this recipe uses; S&B gives water and four to five minutes for its own powder. Those are directions for particular products, and there is no single rule, fifteen minutes or any other, that fits every tin. A short wait before any acid goes in can change how hot the paste becomes, but nothing ferments in that time and nothing is made safer: the paste is simply reaching the pungency it was mixed for. Temperature works against it. Heating can inactivate the enzyme and alter the volatile fraction that carries the heat, so a fresh hot paste is mixed without heat and cooking is kept for milder, cooked styles.

Fierce in the nose, not sour

Heat and sourness are separate sensations, and English mustard shows the difference better than any other. A freshly mixed paste can feel fierce in the nose without tasting particularly of vinegar, while a cooked American yellow mustard can be distinctly sour yet comparatively mild. Sugar, salt, seed variety, grinding, the timing of the acid and cooking each move one of those sensations, so a useful comparison names the one that changed instead of calling every mustard stronger or weaker.

Labels make the same point about sweetness. French's current US yellow mustard lists vinegar, water, mustard seed, salt and seasonings, with no added sweetener, while Colman's prepared English mustard contains sugar. Each label establishes what that one product contains. Neither says what every American or every Briton prefers, and an American condiment is not sweeter by nature: the yellow mustard is one of the plainest on the shelf.

The powder, the jar and the label

Ten grams of powder to fifteen of water gives a thick cream that sits on the plate without running; up to five grams more water loosens it if it comes out too stiff. Make it close to the meal and put out a little at a time beside roast beef or ham, or spread it very thinly in a sandwich. The quantities are small on purpose. The paste is meant for the meal it was mixed for, and nobody has established how long a water-only mustard keeps.

Do not expect it to taste like the jar. Colman's own route to fresh mustard is its powder mixed with cold water and briefly rested, and that is a different thing from its ready-prepared English mustard, whose UK jar lists 21% mustard flour with sugar, salt, wheat flour, turmeric, citric acid and xanthan: sweetness, acid and texture modifiers that a powder-and-water paste does not have. The jar is a smooth hot mustard with some sweetness; the paste is fresh, direct heat. Nor does the paste share the jar's storage life. A commercial prepared mustard is kept as its own label directs after opening, and its heat treatment, preservatives and shelf-life assessment cannot be read from its taste. The dry tin has its own rules too: keep the unused powder dry, tightly closed and within its date, and remember that those instructions stop applying once water has been added.

Read the tin before you start. A packet sold as mustard powder may be pure mustard flour, a blend of seed types, or mustard with turmeric or other ingredients. The Colman's foodservice powder lists mustard flour; S&B's foodservice powder lists mustard flour and turmeric; and The Woks of Life notes that the Chinese dry mustard powder sold in Asian grocers is usually dry mustard with some turmeric. Colour is no guide to the seed, since turmeric supplies a bright yellow and some brown-mustard cultivars have pale seeds, so check the label before substituting one powder for another by weight. This recipe has not been kitchen-tested or tasted against Colman's or any other benchmark: treat it as a starting point, mixed fresh for one meal at a time.