Cut chicken into 1" cubes and place in a large skillet.
Add reserved pineapple juice, chicken broth, vinegar, brown sugar, soy sauce, and garlic. Cover and simmer over low heat (250 degrees for an electric skillet) for 10 minutes or until chicken is no longer pink when cut.
Add vegetables and pineapple; cook an additional 5 minutes.
Combine cornstarch with water and stir until smooth. Slowly pour into hot mixture, stirring constantly, until thickened, about 1 minute more.
Refrigerate leftovers within 2 hours.
Notes
Serve over hot, cooked rice or pasta.
Broth can be canned or made using bouillon. For each cup of broth use 1 cup very hot water and 1 teaspoon or 1 cube bouillon.