How do I make horseradish sauce?

Horseradish heat is not present in the root — it is created the moment the cells are broken, when an enzyme and a compound that were kept apart meet and produce the volatile that makes your eyes water. That reaction peaks within minutes and then decays, which explains everything about how the sauce behaves.

Safety

What you'll need

• Fresh horseradish root, or a jar of grated horseradish
• Crème fraîche or double cream
• White wine vinegar
• Dijon or English mustard (optional)
• Fine grater or food processor

Step by step

1. Peel and grate the root finely, with ventilation.A fine microplane or a food processor. The fumes are genuinely strong — much worse than onion — so work near an open window and keep your face away when you lift a processor lid.
2. Mix the grated root with vinegar straight away.A teaspoon or two of white wine vinegar per two tablespoons of grated root. Acid stops the enzyme reaction and fixes the heat at its current level. Added immediately you get a milder sauce; wait three minutes and you get a fiercer one.
3. Fold it into the dairy.Two to three tablespoons of the vinegared horseradish into 150g of crème fraîche, or into double cream lightly whipped to soft peaks. Cream gives a richer, softer sauce; crème fraîche a sharper one.
4. Season with mustard, salt and a pinch of sugar.A teaspoon of Dijon adds body and a second layer of heat. Salt is essential. A pinch of sugar rounds off the harshness. Taste and adjust — this is where the sauce is made or lost.
5. Rest it briefly, then taste again.Twenty minutes lets the flavours come together. Note that it also mellows, so if you want it fierce at the table, make it close to serving.
6. For jarred horseradish, drain it and boost it.Jarred grated horseradish is preserved in vinegar and is already mild. Drain it, use more than you think, and add a little mustard and black pepper to compensate for the heat that has already gone.

Tips

• Heat degrades with time, air and heat. A sauce made an hour ahead will be noticeably milder than the same sauce made ten minutes ahead, and one that has been in the fridge a week will be mild indeed.
• Never cook horseradish if you want the heat. Warming it destroys the volatile compound almost immediately, which is why horseradish is added to a hot dish at the very end.
• Fresh root keeps for weeks wrapped in the fridge and months in the freezer. Grate it from frozen straight into a sauce.
• Horseradish grows extremely vigorously and is nearly impossible to remove once established. Grow it in a deep container if you want it in the garden.
• The classic partners are roast beef, smoked mackerel, beetroot and boiled potatoes. Beetroot and horseradish blended together is a very good version of both.

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