Drain pineapple, reserving juice. Add water to juice if needed to measure 1 cup; pour liquid into a large skillet. Add ⅓ cup water, vinegar, soy sauce, brown sugar and cornstarch; stir mixture until smooth.
Cook over medium heat until thick, stirring constantly.
Add the pineapple, meatballs and green pepper.
Simmer, uncovered, until heated through, about 20 minutes. Serve with rice.
