
Preheat oven to 400 degrees Fahrenheit. Rub the 5-6 pounds boneless lamb roast with salt and pepper and set in a roasting dish.
In a small bowl, mix 1 cup softened unsalted butter, 5 cloves minced garlic, 1 tablespoon finely chopped thyme, 1 tablespoon finely chopped oregano, 1 tablespoon finely chopped rosemary, 1 tablespoon sea salt, and 1 teaspoon pepper. Rub all of the butter mixture on the outside of the lamb.
Toss the 2 pounds baby potatoes with 1 tablespoon olive oil, and salt and pepper and place them in the roasting dish with the lamb.
Roast in the oven until the internal temperature of the lamb reaches 145 degrees Fahrenheit,1 ½-2 hours.