One of the 'five mother' sauces, Hollandaise is made with an emulsion of egg yolks, butter and lemon juice, usually in a double boiler to prevent overheating, and served warm.

Basic Hollandaise with Variations

4 egg yolks
1 tablespoon fresh lemon juice
1/2 cup unsalted butter, melted and cooled to room temperature
Salt

1. Vigorously whisk, or beat with an electric mixer, the egg yolks and lemon juice together in a stainless steel bowl until the mixture is thickened. Place the bowl over a saucepan of barely simmering water (or use a double boiler - do not allow the water to touch the bottom of the bowl or pan). Continue to whisk rapidly, being careful not to let the mixture get too hot or the eggs will scramble. Slowly drizzle in the melted butter and continue to whisk until the sauce is thickened and doubled in volume. Remove from heat and season to taste with salt. Serve warm.

Makes about 1 cup.

Variations:

Béarnaise Sauce: Stir in 1 tablespoon dry white wine with the lemon juice. After sauce thickens, stir in 1 tablespoon finely chopped onion, 1 1/2 teaspoons chopped fresh or 1/2 teaspoon dried tarragon leaves and 1 1/2 teaspoons chopped fresh or 1/4 teaspoon dried chervil leaves.

Maltaise Sauce: After sauce thickens, stir in 1/2 teaspoon grated orange peel and 2 tablespoons orange juice.

Mousseline Sauce: Prepare Hollandaise Sauce and cool to room temperature. Just before serving, beat 1/4 cup heavy whipping cream until stiff peaks form and fold into the cooled sauce.