Harvard Beets

3 cups cooked diced beets
1/2 cup granulated sugar
1 tablespoon cornstarch
1 teaspoon salt
1/4 cup vinegar
1/4 cup water
2 tablespoons butter

Mix the sugar, salt and cornstarch. Add vinegar and water and stir until smooth. Cook for 5 minutes. Add beets to the hot sauce and let stand for 30 minutes. Just before serving, bring to a boil and add butter.