Caper sauce
Into a cupful of good drawn butter stir a great spoonful of minced capers and a teaspoonful of onion juice.
Maître d’hôtel sauce
Beat two tablespoonfuls of soft butter to a cream with the juice of half a lemon and a tablespoonful of finely-minced parsley. It should be a fine, pale green when done. Serve cold with hot fish.