Preheat your oven to 325°F

To a roasting dish, add the onion and garlic on the bottom then place the lamb on top

Make a few small slits in the thicker parts of the lamb and insert garlic cloves and rosemary

Add mayo and seasoning to the lamb and massage well to incorporate

Add more rosemary and thyme leaves on top of lamb followed by beef broth

Cover the dish tightly and bake for 3 hours or until meat easily pulls away with a fork

Last hour of cooking, add potatoes and carrots and cook until tender