In a medium bowl, whisk together extra-virgin olive oil, freshly squeezed lemon juice, crushed garlic cloves, dried oregano, kosher salt, and freshly ground black pepper until well combined. Pour the marinade into a sealable plastic bag and set aside while you prepare the lamb.

Carefully place the butterflied boneless leg of lamb into the marinade bag, ensuring it’s evenly coated. Seal the bag, pressing out excess air, and refrigerate for at least 8 hours, ideally 24 hours.

About 30 minutes before grilling, prepare your grill for direct heat. If using charcoal, light the coals and let them burn until covered with gray ash. For gas grills, set the burners to moderate heat.

Retrieve the marinated lamb from the refrigerator and remove it from the bag, discarding the marinade. Thread the lamb onto skewers, spacing the pieces about 2 inches apart.

Place the skewered lamb on the hot grill. Cover the grill and cook for approximately 8 to 14 minutes, turning occasionally, until the internal temperature reaches 125-128°F for medium-rare.

Once the lamb has reached desired doneness, carefully remove it from the grill. Cover loosely with aluminum foil and let it rest for 20 minutes.

After resting, slice the lamb against the grain into thick, juicy pieces. Arrange the slices on a serving platter alongside grilled lemon halves.