In medium saucepan, combine rhubarb, sugar and water; mix well. Bring to a boil. Reduce heat to medium-low; simmer 5 minutes, stirring occasionally.
Add strawberries; cook and stir 1 to 2 minutes or until berries are thawed. Serve sauce warm or cool.
To serve, place sponge cake cups on individual large dessert plates. Place 1/2 cup ice cream in each cake cup. Spoon about 1/3 cup strawberry-rhubarb sauce over each.