Combine the first three ingredients in a medium saucepan; bring to a boil.

Reduce heat, and simmer, uncovered, 5 minutes or until rhubarb is tender.

Combine 1 tablespoon water and cornstarch; stir well, and add to rhubarb mixture. Bring to a boil, and cook 1 minute or until thickened, stirring constantly.

Remove from heat; stir in strawberries and vanilla.

Serve warm or chilled over angel food cake, sponge cake, or vanilla ice cream.

Makes ~3 pints.