1Cut the chicken breast into bite-sized pieces.
Dice the red and green bell peppers.
In a bowl, mix the rice vinegar, ketchup, soy sauce, and brown sugar to create the sweet and sour sauce.
In a separate bowl, dissolve the cornstarch in a small amount of water to create a slurry.
Heat a large skillet or wok over medium-high heat and add a small amount of oil.
Add the chicken pieces to the skillet and cook until they are no longer pink, about 5-7 minutes.
Add the diced bell peppers and pineapple chunks to the skillet and cook for an additional 3-4 minutes.
Pour the sweet and sour sauce over the chicken and vegetables, stirring to coat everything evenly.
Add the cornstarch slurry to the skillet and stir until the sauce thickens, about 1-2 minutes.
Serve the sweet and sour chicken over rice or noodles, if desired.