Making your own sweet and sour sauce is easy and economical and starts with ingredients you probably already have in your pantry. All you need is some sugar, apple cider vinegar, ketchup, and a dash of soy sauce.
In a small saucepan, combine the first five ingredients. Bring to a boil; cook and stir until sugar is dissolved.
Meanwhile, using a sharp knife, cut through the two wing joints; discard wing tips. Transfer wings to a 5-qt. slow cooker; add sugar mixture. Cover and cook on low until chicken juices run clear, 3 to 3-1/2 hours.
Transfer wings to a serving dish; keep warm. Skim fat from cooking juices; transfer to a small saucepan. Bring liquid to a boil. Combine cornstarch and water until smooth. Gradually stir into pan. Bring to a boil; cook and stir until thickened, about 2 minutes. [See Note]
Spoon thickened sauce over chicken. Serve with a slotted spoon.
If you use pineapple chunks with juice, decrease sugar to 1/2 cup. If the sauce is not sweet enough in the end you can always add more.
Pineapple and green bell pepper are optional. If you add pineapple, see note 1.
If you prefer, you can thicken the sauce with cornstarch instead of boiling it to thicken. Skim the fat off the top of the sauce with a serving spoon. In a small dish, add 1 -2 tbsp of cornstarch with 1-2 tbsp cold water and mix until combined. Add cornstarch mixture into the crockpot. Stirring to combine with the sauce. The sauce should thicken pretty quickly, about 1-2 minutes.