Cook your chicken and rice according to packages and your preferences.
Pour the pineapple juice from the can, reserving 1⅓ cup. If you don't have quite enough, top off with a bit of water. Set the pineapple itself aside for later.
Combine the brown sugar and corn starch in a bowl and set aside.
To the pineapple juice, add the vinegar, soy sauce, and ketchup. Stir until fully mixed.
Add the brown sugar and corn starch mixture and stir until smooth and mixed.
Add the oil to a sauce pan, deep skillet, or dutch oven on medium-high. Add in the onion and cabbage (or pepper) and saute until tender.
Pour your sauce mixture over the cabbage slowly. Bring it to a boil and stir until it thickens, about 5-10 minutes.
Add your pineapple chunks and chicken to the sauce mixture and let cook for a minute or two, to ensure everything is evenly hot.
Serve over rice and enjoy!