For this recipe use fish with rather firm flesh such as skate pollack, conger eel, hake, turbot, halibut.
Leave the fish to get cold in the Court Bouillon in which it has been cooked.
Cut it in thin slices, and steep for 1 hour in a sauce made from oil, three parts to one of vinegar, one of lemon juice, chopped onion, salt and pepper.
Now dice the fish, and mix with some sliced cooked beetroot, some thin slices of radish, gherkin or pickles.
Garnish with lettuce leaves.