SAUCE HOLLANDAISE

Mix one tablespoon of butter and one of flour in a saucepan and add gradually half a pint of boiling water. Stir until it just reaches the boiling point; take from the fire and add the yolks of two eggs. Into another saucepan put a slice of onion, a bay leaf, and a clove of garlic; add four tablespoons of vinegar, and stand this over the fire
until the vinegar is reduced one-half. Turn this into the sauce, stir for a moment; strain through a fine sieve; add half a teaspoon of salt and serve. This sauce may be varied by adding lemon juice instead of vinegar, or by using the water in which the fish was boiled. It is one of the daintiest of all sauces.