Generously rub the leg of lamb with salt and pepper. Place it in a roasting dish and broil 6 inches from heat for 10 minutes per side.
Remove from oven and turn the oven to 350 degrees. Place the potatoes, garlic, carrots, celery, rosemary, and onions around the leg of lamb.
Pour the chicken broth and white wine over top of the lamb and vegetables.
Cover the dish with foil and bake for one hour. Flip the lamb over and recover the dish, cooking for an additional hour.
Check the temperature of the lamb. You want it to be around 145 or 150. If it's not at that temperature place it back in the oven for 30 minutes.
Remove from oven and slice the lamb. Serve with potatoes, vegetables, and the pan juices.