Cut beef into eight 1 1/2-inch cubes.
Mix lemon juice, olive oil, bay leaves, chopped garlic, salt, pepper and cumin. Pour over beef cubes. Cover. Refrigerate 8 hours or overnight.
On two skewers, alternate beef cubes, tomatoes and onions. Cook over hot coals or under broiler about 15 minutes, turning every 5 minutes.
Serve over hot, cooked rice.