Whisk Mojo Sauce ingredients in small bowl. Set aside.
Cut beef steak into 1-1/4 inch pieces; season with pepper.
Alternately thread beef with lime and onion wedges evenly onto four 12-inch metal skewers. Thread tomatoes evenly onto four 12-inch metal skewers.
Place kabobs on grid over medium, ash-covered coals. Grill tomato kabobs, covered, about 2 to 4 minutes or until slightly softened, turning occasionally. Grill beef kabobs, covered, 8 to 10 minutes (over medium heat on preheated gas grill 9 to 11 minutes) for medium rare (145 degrees F) to medium (160 degrees F) doneness, turning once.