Preheat oven to 180 degrees Celsius
Bring lamb to room temperature. Pat lamb dry with paper towels.
In a small bowl, combine the thyme, mustard, minced garlic, salt and pepper. Set aside
Use a sharp knife and make deep indents in the lamb. About 6 on each side
Stuff a piece of garlic, a small piece of rosemary and a clove in each indent
Rub the marinade all over the lamb
Place some foil in a roasting pan. Place the lamb inside, fatty side up and pour the stock into the pan. Cover with a piece of foil and cook in the oven for 2 hours
After 2 hours remove the foil and flip the lamb over. Cook for another 1 hour or until cooked to your liking