In a medium bowl, whisk together 1 tablespoon of cornstarch and water until combined. Whisk in rice wine vinegar, ketchup, soy sauce, brown sugar and reserved pineapple juice.
In a large skillet heat the vegetable oil over medium high heat. Toss the chicken in the remaining 1/2 tablespoon of cornstarch and season with salt and pepper.
Add to the skillet and cook without stirring for 2-3 minutes. Mix and continue to cook for 6 -7 minutes. With a slotted spoon transfer the chicken to a plate.
Add red bell pepper, green bell pepper and onion to the skillet; cook for 3 minutes or until vegetables soften. Season with salt and pepper. Stir in the sweet and sour sauce mixture, along with the pineapple chunks. Cook for another 1 to 2 minutes to warm thoroughly and allow the sauce to thicken slightly. Add the chicken back to the skillet and stir to combine.
Serve over cooked white rice.
Recipe from Good Fast Eats by Amy Flanigan. Nutrition information does not include rice.