Bilad al-Sham Kitchen - Roast with Mashed Potatoes and Vegetables

Recipe Ingredients:

- 1 beef roast- 3 carrots- 3 tablespoons of mustard- Salt and pepper- 2 tablespoons of oil- 1 tablespoon of butter- 3 onions- 6 garlic cloves- Rosemary- 2 celery stalks- 2 cinnamon sticks- Bay leaves- For the sauce: - 1 tablespoon of butter - 3 cups of mushrooms- For serving: - Mashed potatoes - Vegetables