Baked Harvard Beets

3 cups cooked beets, diced
1/4 cup sugar
1 Tbsp. cornstarch
1/2 tsp. salt
1/3 cup vinegar
1 Tbsp. lemon juice
3 Tbsp. beet juice
2 1/2 Tbsp. butter

Place beets in casserole dish. Combine constarch, sugar, and salt. Add vinegar, lemon juice, and beet juice. Mix thoroughly. Pour over beets and dot with butter. Cover casserole and place on lower oven rack in 350 degree oven for 1 hour.