1. In a large nonreactive bowl, combine soy sauce, vinegar, dipping oil, rosemary, pepper, and cumin.
2. Cut trimmed lamb into 1-inch cubes and add to marinade, making sure marinade coats lamb pieces completely. Cover with plastic wrap and refrigerate for at least 2 hours or, preferably, overnight.
3. Remove lamb from refrigerator and preheat broiler or grill. Place 3 pieces of lamb on small metal or presoaked wooden skewers, with a tomato on each side of the center piece of lamb. Lamb and tomatoes should be placed toward one end of skewer, allowing the other end to be a handle for serving. There should be enough lamb and tomatoes to make about 14 to 18 skewers.
4. Place skewers on a baking sheet and broil, or grill on medium-high direct heat, for about 3 to 4 minutes on each side, or until lamb is cooked through. Medium-rare meat is best; lamb should still be slightly pink inside. Serve hot with dipping sauce on the side.
Note: You will need metal or bamboo skewers. If using bamboo skewers, be sure to soak them in cold water for about 30 minutes before placing the lamb on them or they will burn.
Source: Hannaford fresh Magazine, November - December 2007