Cut the lamb shoulder into 1-inch cubes and season with salt and pepper.

Chop the onion, mince the garlic, slice the carrots and celery, and cube the potatoes.

In a Dutch oven, heat the olive oil over medium-high heat. Add the lamb cubes in batches and brown on all sides. Remove and set aside.

In the same pot, add the onion and sauté until translucent. Add garlic, carrots, and celery, cooking for another 5 minutes.

Return the browned lamb to the pot. Add the potatoes, beef broth, red wine, thyme, rosemary, and bay leaf. Stir to combine.

Bring the stew to a boil, then reduce heat to low. Cover and let simmer for about 2 hours, or until the lamb is tender.

Remove the bay leaf before serving. Adjust seasoning with salt and pepper to taste. Serve hot.