Mix together 1 cup granulated sugar, 3 or 4 tablespoons vinegar, 2 teaspoons lemon extract, 2 level tablespoons cornstarch and slowly add 2 cups boiling water, stirring constantly on stove until mixture gets thick. When cold stir in yolks of 2 eggs and pour into 2 pie tins lined with good pastry. When baked, cool and cover with the whites of egg and sugar. Brown in a quick oven.