Add the following to a food processor, garlic, red wine, lemon juice, olive oil, salt, pepper, allspice, and seven spice. 

Pour the marinade over the meat. Marinate for at least four hours.

Skewer the meat on metal skewers, alternating with the onions and peppers. If you don't have metal skewers, I highly recommend them. If you would rather use wooden skewers, make sure you soak them in warm water for 20-30 minutes before using them. 

Sprinkle the skewered meat with 2 teaspoons of sumac.

Barbecue over medium heat until the meat is cooked to your liking.

Serve over rice with my Thai Peanut sauce