Place the garlic, mint, turmeric, coriander, cumin, lemon zest, and 2 1/2 teaspoons salt in the bowl of a food processor fitted with the steel blade and process until finely ground. Add the olive oil and pulse to combine.
Place the chops in one or two non-metal dishes large enough to hold them in one layer. Spread the garlic and herb mixture evenly on both sides. In a small bowl, whisk together the yogurt, Sriracha, and lemon juice, and spread it evenly on the lamb chops. Cover, refrigerate, and allow to marinate for 6 to 24 hours.
Prepare a charcoal grill with hot coals and oil the cooking grate. Sprinkle the lamb with salt and grill 5 to 6 inches above the coals, first with the yogurt side up (marinade and all) for 4 to 5 minutes, then turn and grill for 3 to 4 minutes, until medium rare. Transfer to a clean plate, cover the plate tightly with aluminum foil, and allow to rest for 10 minutes. Sprinkle with salt and serve hot with the couscous.
Couscous With Pine Nuts and Mint:
Heat the oil and butter in a large saucepan over medium heat. Add the onion and cook over medium-low heat for 6 to 8 minutes, stirring occasionally, until tender but not browned. Add the stock and bring to a boil. Stir in the couscous, 1 teaspoon salt, and 1/2 teaspoon pepper and remove from the heat. Cover the pot tightly and allow the couscous to steam for 10 minutes. Fluff the couscous with a fork and stir in the mint and pine nuts. Taste for seasonings and add about 1 teaspoon salt, depending on the saltiness of the stock, and 1/2 teaspoon pepper. Serve hot.