Cut lamb into 2-inch cubes; toss with onion and garlic in a bowl.
Cut fat from lamb into slivers.
Combine pomegranate juice with salt and pour over lamb (meat and fat), set in a cool place (but NOT cold like refrigerator) and marinate 4-12 hours.
After marinating lamb, pat each piece dry as you place it on 6 long skewers, interspersing lamb fat slivers with meat cubes; put a cube of bread at the end of each skewer to hold the meat on the skewer.
Brush each skewer's contents with oil and sprinkle with pepper to taste.
Grill (traditional) or broil 12-20 minutes from very high heat, turning once and basting with any juice that runs off, until meat is cooked through.
Slip meat directly off skewer onto plate, one plate for each person being served.