Bring 1 liter of water to a boil with the bouillon cubes. Peel and chop the celery and carrot into pieces.
Preheat the oven to 350°F (180°C). Place the lamb shoulder in a large roasting pan. Rub it with olive oil, salt, and pepper. Pour the wine and bouillon around the lamb and add the celery and carrot. Cover the pan with aluminum foil and bake for 1 hour 45 minutes.
Halve and pit the apricots. Peel and quarter the potatoes. Seed and slice the bell pepper.
Remove the pan from the oven, take off the aluminum foil, and add the potatoes, apricots, and bell pepper. Mix well and cover the pan again with aluminum foil. Bake for another 45 minutes.
Remove the aluminum foil and increase the oven temperature to 430°F (220°C). Finish cooking for an additional 30 minutes to brown the meat well.
Serve the tender lamb shoulder hot with the apricots, potatoes, bell pepper, aromatic garnish, and the broth.