Lamb Shish Kebab

Cut lamb leg into ½ inch cubes.
In a large mixing bowl, mix together marinade ingredients.
Add lamb to marinade, mix, cover, and refrigerate for a minimum of 4 hours and up to 24 hours.
Make onion garnish by mixing sliced red onion, lemon juice and salt. Combine well and let stand, covered, while lamb marinates.
Before grilling, make yogurt sauce by combining 1 cup plain yogurt, mint and grated cucumber. Set aside.
In a small bowl, combine salt, cumin and sumac.
Prepare grill for charcoal or preheat gas grill.
Prepare skewers by alternating 3 pieces of lamb with 1 piece of beef or lamb fat
Grill peppers until nicely charged, then remove from heat and put aside.
If desired, grill onion halves and small tomatoes.
Place skewers on the grill or suspend them over the coals.
Grill, turning often, until lamb is cooked through and lightly charred in places, about 10-20 minutes, depending on how hot your grill is.
Near the end of cooking, place pieces of lavash bread over the lamb. Heat for 30-60 seconds, turning often to prevent burning. Remove from heat and place on a baking tray.
Remove skewers from grill and place on the lavash bread on the baking tray. Sprinkle meat with the salt/cumin/sumac mixture to taste.
Peel charred skin from hot peppers.
Remove meat from skewers and serve with lavash bread, yogurt sauce, lemon-pickled red onions, grilled hot peppers, grilled onions, and grilled tomatoes. Top with fresh parsley, if desired.