Lahem Meshwy (Lamb Shish Kebabs)

Pat lamb dry using paper towels, and place in a large bowl. Add 3 tablespoons oil, 1 tablespoon salt, 1/2 teaspoon paprika, and 1/4 teaspoon black pepper to lamb; toss until well combined. Cover bowl with plastic wrap; refrigerate at least 2 hours or up to 24 hours. Remove lamb from refrigerator, and let stand at room temperature 30 minutes.

Meanwhile, preheat grill to medium-high (400°F to 450°F). Cut onion in half lengthwise. Slice each half into 1-inch-thick wedges, slicing into only the first 3 or 4 outer layers; reserve remaining onion core for another use. Combine onion wedges, bell peppers, mushrooms, tomatoes, remaining 3 tablespoons oil, remaining 1 tablespoon salt, remaining 1/2 teaspoon paprika, and remaining 1/4 teaspoon black pepper in a large bowl; gently toss to coat. Set aside until ready to use.

Thread about 5 lamb cubes onto each of 10 (8-inch) wooden skewers, making sure to keep at least 1/4 inch of space between cubes to promote even cooking. Thread onion wedges, bell peppers, and mushrooms evenly onto 4 (8-inch) wooden skewers. Thread tomatoes onto 2 (8-inch) wooden skewers. Place lamb skewers on lightly oiled grill grates; grill, uncovered, turning occasionally, until well browned on all sides and slightly pink in the middle, 8 to 10 minutes. Transfer grilled lamb skewers to a platter. Place vegetable skewers on lightly oiled grates; grill, uncovered, turning occasionally, until tender and lightly charred, 6 to 8 minutes for tomato skewers and 10 to 12 minutes for mixed vegetable skewers. Transfer grilled vegetable skewers to platter with lamb.

Cut each pita in half lengthwise, and split each pita half at the seam. Spread about 3 tablespoons muhammara over each pita piece, and top each with about 1/3 cup grilled lamb, about 1/4 cup grilled vegetables, and about 1/4 cup biwaz. Fold pitas in half, and serve.