Combine chili powder, cumin, salt, oregano and garlic in small mixing bowl. sprinkle spice mixture over meat, pressing into surface. Arrange coals for indirect cooking. Place meat on grill, cover and grill for 30 to 45 minutes until thermometer registers 160F. Spray onion slices with olive oil cooking spray and place on the grill rack over coals last 10 to 15 minutes of grilling time. Slice pork and serve pork and grilled onions with Corn and Black Bean Salsa.