Marinate the Lamb: Combine olive oil, garlic, lemon juice, oregano, salt, and pepper. Coat the lamb and let it marinate for at least 4 hours (overnight is best).
Prepare the Grill: Preheat the grill to medium heat. If using a spit, skewer the lamb securely.
Grill the Lamb: Place the lamb on the grill or spit. Cook for about 1.5-2 hours, turning occasionally. Baste with the marinade every 30 minutes.
Check Doneness: Use a meat thermometer if desired—aim for 135°F for medium-rare.
Rest and Serve: Let the lamb rest for 10-15 minutes before slicing. Serve with your favorite sides.