Prepare the grill (don't forget to spray with oil before the fire is lit.) Combine ingredients, cumin through garlic in a dish or plastic bag. Spray the meat cubes with olive oil spray or brush lightly with the olive oil. Toss the meat cubes in the rub, either in the plastic bag or roll the cubes in the dish.
Let the meat "age" in the refrigerator for up to 20 minutes.
Thread the meat cubes and onion wedges onto skewers alternately. Grill kebabs on the grill rack for 4–5 minutes on each side, or until the meat reaches the desired degree of doneness.