In a bowl combine vinaigrette, garlic, oregano and red pepper flakes with a whisk. In a ziplockbag combine lamb pieces with vinaigrette. Refrigerate and marinate overnight.
Drain meat and pat dry. Heat grill pan over medium high heat. Skewer the lamb pieces alternating with tomatoes, red onion and green bell pepper. Grill for 2 minutes per side rotating four times.
Recipe courtesy of Gourmet Magazine