Preheat the oven to 375°F (190°C).

Pat the leg of lamb dry with paper towels and place it in a roasting pan.

Make small incisions in the meat and insert garlic slices and rosemary into the slits.

Rub the lamb with olive oil, salt, and black pepper.

Arrange the chopped vegetables and thyme around the lamb in the roasting pan.

Pour the red wine and beef broth into the pan.

Roast in the preheated oven for about 90 minutes, or until the internal temperature reaches 135°F (57°C) for medium-rare.

Baste the lamb with the pan juices every 30 minutes.

Remove the lamb from the oven and let it rest for 15 minutes before carving.

Slice the lamb against the grain and serve with the roasted vegetables and pan juices.