Preheat the oven to 340°F. Spread the chopped onion and carrot across the bottom of a roasting dish. Add the halved garlic and fresh herb sprigs.
Pat the lamb dry, then rub it with olive oil. Season with salt and pepper, then turn the lambs the other side and repeat the process. The lamb should be evenly coated on all sides.
Place the seasoned lamb on top of the vegetables. Pour the broth into the bottom of the pan around the meat.
Cover the dish tightly with foil and cook for about 4 hours, until the meat becomes tender.
Increase the oven temperature to 400°F. Remove the foil and roast for another 15 minutes to brown the outside.
Take the lamb out of the oven, loosely cover it again with foil, and let it rest for 30 minutes before serving.
Make the gravy
Melt butter in a saucepan over medium heat. Stir in the flour and cook briefly until smooth and slightly golden.
Slowly whisk in the strained pan juices. Continue whisking until the gravy thickens and becomes smooth.
Shred or slice the lamb and serve warm with the gravy spooned over the top.
Notes
Cooking at a lower temperature first helps break down the lamb, making it tender and easy to pull apart.Don’t skip the rest time: Letting the meat rest keeps it juicy and makes slicing easier.
Beef broth adds depth, but chicken or vegetable broth works fine.For a silky texture, strain the pan drippings before adding to the gravy.Extra flavor tip: Lightly crush the garlic before adding it to release more flavor into the roast.
The lamb is ready when it pulls away easily from the bone.