In a small saucepan combine sugar and orange juice. Bring to boiling; add fresh or frozen rhubarb. Return to boiling; reduce heat. Cover and simmer for 5 to 7 minutes or until rhubarb is nearly tender. Drain rhubarb, reserving syrup.
If necessary, add water to reserved syrup to make 2/3 cup. Pour syrup into saucepan. Stir together cornstarch and the water; stir into syrup. Cook and stir until thickened and bubbly. Cook and stir for 2 minutes more. Remove saucepan from the heat.
Gently stir in rhubarb and strawberries. Cover and chill 1 1/2 to 6 hours. Makes 6 servings.