Peel beets. Cook in a four-quart saucepan for one and a half hours or until tender. Reserve six  tablespoons of liquid.

In small saucepan, mix sugar, lemon juice, and beet liquid. Add cornstarch and bring to a boil.

Add margarine and cook for five to six minutes. Pour mixture over sliced beets and let stand for several hours or overnight to marinate. Serve warm.