In a medium bowl (microwave safe) cook onions and peppers in microwave for 2 minutes, to soften.
To the bowl of cooked onions and peppers, stir in pineapple juice, brown sugar or honey, soy sauce and garlic. Mix well.
Place chicken thighs into crock-pot. Stir in pineapple juice/veggie mixture. Top with pineapple chunks with juice. Cover and cook on low heat for about 4 hours or high heat 1-½ -2 hours. You can baste during cooking time, if desired. Cook time varies depending on your crock-pot.
Once chicken is cooked: In a small bowl, whisk together 2 tablespoons water and cornstarch, to dissolve. In the crock-pot, stir dissolved cornstarch into sauce of cooked chicken. Cover and cook on high heat for an additional 30 minutes, or until sauce is thickened a bit. Or, remove sauce from crock-pot and add to a small pot. Stir in dissolved cornstarch. Simmer until a little thickened. Stir often. Add sauce back to chicken.