This recipe uses the onion confit
and garlic confit
; you may substitute 1/2 cup sautéed sliced onions and 3 minced cloves of garlic.
Place lamb fat side down on a baking sheet. Combine salt, pepper, cumin, coriander, and mint in a bowl. Sprinkle half on lamb, and spread onion and garlic confits on top. Roll up lamb lengthwise like a jelly roll; maintain its shape by tying with kitchen string every 1 1/2 inches. Rub outside with oil and sprinkle rest of spice mix on top. Let sit at room temperature for 1 hour before grilling.
Preheat grill to medium-high and pile all coals on one side. Place lamb above coals, and sear each side 3 to 4 minutes until browned and slightly charred.
Move lamb to other side of grill and put lid on with vents open. Cook about 1 hour and 15 minutes, flipping every 15 minutes. When almost done, place a thermometer in the thickest part; it should be 130° for medium rare. Remove lamb from grill and let sit 20 minutes before slicing.
Meanwhile, make chutney by boiling 3 cups of water in a medium saucepan. Add onions and boil 1 minute, then strain. When cool enough to handle, peel onions; if some are much larger than others, cut them in half lengthwise.
In a large sauté pan, heat oil over medium heat. Add onions and sauté, stirring often, until slightly soft, 7 to 10 minutes. Add garlic, ginger, and red pepper; stir for 30 seconds. Add honey and vinegar, then bring to a boil. Reduce heat to low and gently stir in plums; simmer until thickened, about 5 minutes. Sprinkle with cilantro and salt. Remove from heat; cool in pan.
When lamb is ready to be served, remove strings, cut into thick slices, and serve with chutney on the side.