By William Lander, Shaun Searley and Daniel Morgenthau
We love the intense hit of fresh horseradish (we grate it to order on steaks in the restaurant, our equivalent of the comedy-sized black pepper mill in red-sauce Italian joints). Here, it blends very nicely with the acidity of the vinegar and richness of crème fraîche to create an ideal but lesser-spotted accompaniment to roast beef.
Finely grate the horseradish and combine with the rest of the ingredients.
Leave to infuse for at least 1 hour before serving.