Prep: 1. Zest and juice lemon. 1. Make marinade: mix yogurt, olive oil, lemon zest, lemon juice, rosemary, salt, and pepper. 2. Cover lamb with marinade and refrigerate (covered) for 30 minutes or up to overnight. (the longer the better) 3. Cut red onion into large bite sized pieces for skewers. Make 1. Heat grill. 2. Pop lamb onto skewers alternating with red onion. 3. Sprinkle with salt and pepper. 4. Grill for 10 -15 minutes total, turning 2 or 3 times.