1.To make marinade, place cumin, garlic, lemon zest, herbs and 1/4 cup (60ml) oil in a food processor. Season, then whiz to a paste. Spread over the lamb, then chill for at least 3-4 hours to marinate (remove from the fridge 1 hour prior to cooking).
2.Preheat oven to 200°C. Brush off most of marinade and discard. Heat remaining 2 tbs oil in a large frypan over medium-high heat. In batches, cook lamb for 4 minutes each side or until browned. Place the bay leaves in a roasting pan and top with lamb racks. Roast for 8 minutes for medium-rare or until cooked to your liking. Rest, loosely covered with foil, for 10 minutes.
3.Carve the lamb racks and serve with flatbreads sprinkled with zaatar and onion.