1 tb Cornstarch
2 tb Lemon juice, freshly squeezd
1    Salt
1    Cayenne
2 tb Unsalted butter

In the top of a double boiler, slowly whisk 3/4 cup water into the
cornstarch. Stir in the lemon juice, salt and cayenne to taste. Place the
top over simmering water and cook, stirring constantly, until slightly
thickened, 2 to 3 minutes. Remove the top from the heat. Whisk in the egg
yolks, one at a time, and one tablespoon of the butter. Replace over the
water and cook until slighly thickened, about three minutes, stirring
constantly. When ready to serve, whisk in the remaining butter; taste and
correct the seasonings.