There are two types of Horseradish Sauce, Creamed and Pickled. The pickled is more popular in North America; the Creamed is more popular in Britain. The Creamed tends to have a milder taste.
To make creamed horseradish, grated Horseradish is mixed with a double-cream, white sauce or mayonnaise, or any combination of the three. If mayonnaise is used, the ratio of Horseradish used is much higher than that for Horseradish Mayonnaise. In North America, sour cream can be substituted for the double-cream.
Creamed horseradish is also popular in Germany. If it is made by mixing a white sauce base (béchamel) with horseradish and cream, then it is known as “Meerrettichsauce.” If it is made by mixing horseradish (either freshly-grated or pickled) with sour cream or (more commonly) whipping cream, then it’s known as “Meerrettichsahne” (“Meerrettich-Creme” on a fancy restaurant menu.) Either type can be served with beef, or sausages, or fish such as as salmon, carp, and smoked trout. “Preiselbeer-Meerrettichsahne” (Lingonberry creamed horseradish) is served with game.
Made from cream:
3 tablespoons grated horseradish
½ teaspoon prepared mustard
3 tablespoons extra-thick double-cream
Dash of pepper
1 tablespoon white vinegar
Mix the mustard into the cream. Stir in the horseradish, then the vinegar, and chill. For the extra-thick double-cream, you can substitute crème fraîche, Greek yoghurt, sour cream, whipping cream. Whip first if using double-cream or whipping cream to thicken it.
Made from white sauce:
Make 1 cup (8 oz / 250 ml) of white sauce, medium-thickness. While still warm, stir in some butter, a teaspoon of prepared mustard, and grated fresh horseradish. Try anywhere from 2 to 4 tablespoons of grated horseradish, depending on how hot you like it.