Serving suggestion: flatbread, grilled tomatoes, sliced raw onion, rice and sumac.
Place the beef in a large casserole dish. Combine the walnuts, pomegranate syrup, olive oil and garlic in a food processor and grind into a thick puree. Add the parsley and pulse into small bits. Pour the marinade over the meat and toss well. Cover and refrigerate overnight. Cut the marinated meat into small chunks, and thread 3 to 4 pieces onto the skewers, 1/4-inch apart. Brush or wipe the excess marinade from the skewers, and discard the marinade. Turn the grill on high heat. While it heats up, leave the meat out so it can come up to room temperature (no more than 45 minutes total). Lightly oil the hot grill, and grill the kebabs for 6 to 7 minutes, turning once. Sprinkle the kebabs with fine salt and freshly ground black pepper as they cook. The meat should be slightly charred on the outside and very pink on the inside when it is finished. Serve with flatbread, grilled tomatoes, sliced raw onion, rice and sumac.