Sauce Bavaroise (Horseradish and Crayfish Sauce for Fish)

Ingredients

• 5 décilitres vinegar
• a fragment of thyme
• a fragment of bay leaf
• 4 parsley stalks
• 7 to 8 grains coarse pepper
• 2 spoonfuls grated horseradish
• 6 egg yolks
• 400 grammes butter
• 1 and a half spoonfuls water
• 100 grammes Beurre d'Écrevisses
• 2 spoonfuls whipped cream
• crayfish tails

Instructions

1. Reduce the vinegar by half with the thyme, the bay leaf, the parsley stalks, the coarse pepper and the grated horseradish.
2. Add the egg yolks to the reduction.
3. Work the sauce up as for a sauce Hollandaise with the butter, adding the water in small parts as you go.
4. Pass through a tammy cloth.
5. Finish with the Beurre d'Écrevisses, the whipped cream and the diced crayfish tails; the sauce should be foamy.