Cook rice according to package directions except you don’t need to add oil or salt to the water while cooking.
In the meantime, coat the bottom of a nonstick pan with cooking spray. Heat 1 teaspoon oil over medium-high heat. Add garlic, ginger, red pepper flakes, and chicken to pan; sauté 5 minutes or until chicken is done. Remove chicken mixture from pan; set aside.
Coat pan again with cooking spray and heat remaining 1 teaspoon of olive oil. Add onions, carrots, celery, and red bell pepper to the pan. Sauté 3-4 minutes until crisp-tender. Drain pineapple, reserving ¾ cup juice. Add 1½ cups pineapple chunks to pan; cook 30 seconds (Reserve remaining pineapple for another use). Combine the reserved ¾ cup pineapple juice, soy sauce, vinegar, flour or cornstarch, brown sugar and sugar substitute in a bowl, stirring with a whisk until smooth.
Return chicken mixture to pan. Stir in juice mixture; bring to boil. Cook 1-2 minutes until sauce thickens a bit.
To serve: Spread ½ cup rice over each plate. Top each with about 1 cup sweet and sour chicken.
This dish freezes great. Mix together the chicken and rice and freeze in individual servings.