Place beets in a large saucepan; add water to cover. Bring to a boil; cover and cook 15 minutes or until tender. Drain, reserving 1/2 cup liquid.
Combine next 2 ingredients in a saucepan; slowly stir in reserved liquid. Cook over medium heat, stirring until thickened and bubbly. Remove from heat; stir in vinegar and butter. Pour over beets.