Preheat oven to 180°C top and bottom heating.
Remove tendons from lamb and pat dry. Heat clarified butter in a casserole (cast iron or emaille) and sear the lamb from all sides. Remove from the pot and set aside.
Sauté the onion in the same pot. After about 3 minutes add carrots and garlic.
Put the lamb back in dust with flour. Add salt and pepper and continue to fry for about 5 minutes so that the flour slightly browns.
Deglaze with red wine. Now mix in beef stock, tomato passata, tomato paste and brown sugar.
Add herbs and whole tomatoes. Bring to a boil.
Cover and place on the lower rack in the oven. Roast for about 2 hours.