Place potato in a large bowl, and cover with cold water. Let stand 5 minutes. Drain and rinse potato. Dry thoroughly in a salad spinner, or pat dry with paper towels. Combine potato, onions, and bell pepper in bowl. Add the cornstarch, salt, black pepper, and onion powder; toss well to coat.
Line a baking sheet with nonstick aluminum foil; coat thoroughly with cooking spray. Place a 3-inch biscuit cutter on prepared baking sheet. Fill biscuit cutter with 1/2 cup potato mixture (do not pack). Carefully remove cutter, leaving potato patties intact. Repeat the procedure with remaining potato mixture. Coat tops of potato patties with cooking spray. Bake at 475° for 20 minutes. Turn and bake for an additional 15 minutes or until golden brown.