Lemon Sauce

Lemon sauce:
4 teaspoons cornstarch
Few grains salt
1/4 cup white sugar
1-1/2 cups boiling water
2 teaspoons butter
1 teaspoon grated lemon rind
2 tablespoons lemon juice

Lemon sauce:
Combine cornstarch, salt and sugar in a small saucepan. Slowly stir boiling water into the sugar mixture.

Cook over low heat, stirring constantly, until the sauce is smooth and thickened. Cover and cook over very low heat or over boiling water in a double boiler, stirring occasionally, until no raw starch taste remains, about 5 to 7 minutes.

Remove from heat and stir in butter and lemon rind and juice.