1. Place the lamb cubes in a large ziplock bag. In a small bowl, mix the mint, vinaigrette, ¼ T. spicy barbecue sauce, a few drops of Worcestershire sauce, fennel seeds, and garlic. Pour over the lamb. Seal the bag and let marinate in the refrigerator for 1 hour.
2. To prepare the sauce, mix the yogurt, cucumber, 1 t. spicy barbecue sauce, and garlic in a small bowl, then set aside.
3. Thread the lamb onto metal skewers, reserving the marinade. Place the skewers on a grill. Grill at high temperature for 10 to 15 minutes, or until desired doneness, turning and brushing with marinade often. (Do not brush during the last 5 minutes of cooking.)

4. To serve, remove the lamb from the skewers. Place the lamb in the pita bread halves. Top with tomatoes, onions, and yogurt sauce. Season to taste.