Cut pork into 1/2-inch slices.
Seed peppers and slice into quarters.
Slice onion into 6 slices.
Mix pepper, cumin, and garlic powder into the oil.
Preheat stovetop grill.
Brush pork with flavored oil.
Grill pork slices over medium heat, about 1 minute per side.
Place pork on serving dish.
All pinkness should be gone from inside of pork.
Grill peppers and onion slices about 2 minutes per side, or until done to taste, brushing as you turn.
Remove vegetables and arrange with pork.