A tangy yogurt-herb marinade tenderizes this leg of lamb, then browns in the oven to add flavor to the drippings. Top with chunky Almond Relish for a dramatic dish worthy of a holiday feast or special occasion. (Plan ahead: Chef Berglund recommends two days of marination.)
Marinade: Use a spoon to peel the ginger. Peel garlic and onion. Roughly chop onion and ginger, followed by half of the parsley and cilantro, including stems. In a blender, add the ginger, onion, garlic, herbs, ⅓ of the yogurt, and salt. Purée until smooth. Add the remaining yogurt and purée again to combine. Set aside.
Lamb: Place lamb on a flat surface. Use a sharp knife to poke holes in the lamb at 1½-inch intervals; this will help the lamb absorb the marinade. Flip over and repeat on the other side. Fit a brining bag into a large container (or the roasting pan you'll be using, if it fits in the refrigerator). Then place the lamb into the bag and pour in the marinade. Massage the marinade into the lamb so all of the meat is covered, then seal the bag. Refrigerate for 1–2 days (longer marination will yield more tenderized lamb).
Preheat the oven to 350 degrees F. Transfer the lamb and all of the marinade into a roasting pan. Lay parchment paper over the lamb to cover, then cover the roasting pan tightly with aluminum foil. Roast for 1 hour. (Total roasting time will be 3 hours.)
After 1 hour, remove lamb from oven. Gently remove foil and parchment. (The yogurt will have separated into curds and whey, which is normal.) Use tongs to flip the lamb over, then cover with parchment and foil again. Place back into the oven for 1 hour. After the second hour of roasting, flip the lamb again and place back into the oven, uncovered, for 1 final hour.
After a total of 3 hours of roasting, remove lamb. Pierce the lamb with a sharp knife to check for doneness. If there isn’t a lot of resistance, it’s done. Flip lamb over, spoon yogurt solids on top, and let rest, 30 minutes.
Almond Relish: Roughly chop the almonds, place in a medium bowl, and set aside. Pick the leaves off the remaining cilantro and parsley, bunch together, and finely chop. Add herbs to the almonds. Add enough olive oil to cover, about ½ cup, and mix. Juice 3 of the 4 lemon halves into the relish, mix, and add salt to taste. Use the juice of the remaining lemon half to taste.
Assembly: Use tongs and a meat fork to transfer lamb to a serving platter. Spoon relish over the lamb, and serve.