Grate the zest from one of the lemons and squeeze the juice into a small bowl. Place zest into a blender. Cut the other lemon into wedges and save for serving.

Cut one onion into wedges, put into a blender and add lemon zest. Halve remaining onion and slice it thinly. Rinse well with cold water in a sieve. Place in small bowl with lemon juice. Sprinkle lightly with salt, sugar, and cayenne. Toss and refrigerate for at least 6 hours or until serving.

Add yogurt, mint, cilantro, garlic, black pepper, 2 1/2 t kosher salt and 1/8 t cayenne. Blend until smooth.

Prepare lamb by removing from mesh. It should already be butterflied and unfold. Pour marinade, (I reserved some for serving) into a large zip-lock bag and add lamb making sure it is well covered. Refrigerate for at least 6 hours or overnight.

Heat grill. Wipe off most of the marinade from lamb with paper towels. Grill until a meat thermometer registers 115 degrees for rare and 125 for medium, about 6 – 15 minutes per side, depending on how thick the lamb is and how well you like it cooked. I do not recommend cooking it more than medium. The nice thing about lamb is that because it is not of an even thickness, when you grill it, there are some areas that are rare and others that are more cooked. This way there is something for everyone’s tastes. If the meat starts to char before it’s done, move to a cooler part of the grill.

Transfer to a cutting board and tent with foil, letting lamb rest for 10 minutes, before slicing. Spoon any juices over the top. Sprinkle with sea salt, mint leaves and lemon wedges. If you reserved some of the sauce, drizzle that over the top along with the lemon onions. (Drain juice from the onions!)