In large zip-top bag, add lamb, lemon pepper marinade, minced garlic, paprika, and mint. Squeeze out air and let marinade at room temperature for 30 minutes.
Preheat oven to 450 degrees F.
Place sliced onions in bottom of roasting pan. Remove lamb from bag and place on top of onions. Pour marinade mixture over lamb.
Place in preheated oven and immediately reduce heat to 375 degrees F. Roast for approximately 30 minutes per pound or until a meat thermometer inserted into the thickest part of the meat registers 165 degrees F.
Remove from oven and tent with aluminum foil and let rest for 10 minutes before carving.
Serve with Saffron Couscous.
In a medium saucepan, bring broth, saffron, and salt to a boil. Remove from heat and stir in couscous. Cover and set aside for 5 minutes.
Transfer cooked couscous to a medium bowl and fluff with a fork. Add remaining ingredients and toss to combine.