Preheat oven to 350 degrees. Spray a 9 x 13" pan with cooking spray and set aside.
Mix together sauce ingredients and refrigerate until needed.
Wash bell peppers. Cut in half lengthwise and remove seeds. Place peppers in a microwaveable dish and add about 1/4" of water. Microwave for about 3 minutes or until they just start to soften. Remove from microwave & pat dry with paper towels. Place in prepared 13 x 9 pan. Set aside.
To make filling:.
mix together the cumin, garlic powder, salt, pepper, rice, chicken, salsa, black beans, corn, onions and cheese.
Fill the peppers, mounding the stuffing slightly.
Bake uncovered for about 30 minutes or until filling is hot and the peppers are tender.