1Cut pork into 32 (1-inch) pieces; place in medium bowl. In small bowl, mix chili powder, cumin, brown sugar, garlic powder and red pepper. Reserve 2 teaspoons spice mixture; sprinkle remaining mixture over pork pieces; stir to coat completely. Let stand 15 minutes.
2In small bowl, mix mayonnaise, mustard, reserved 2 teaspoons spice mixture and the onion; set aside.
3Heat gas or charcoal grill. Spray grill basket (grill “wok’) with cooking spray. Spoon pork into basket.
4Place basket on grill. Cover grill; cook over medium heat 10 to 12 minutes, shaking basket or stirring pork once or twice, until pork is no longer pink in center. Serve with toothpicks and mayonnaise mixture for dipping.