Rinse the lamb shanks under cold water. Make sure there are no bone fragments left on the meat. Dry with paper towels and sprinkle with lemon juice. Set aside.
Let's prepare the marinade: Grind the salt, pepper mixture and garlic clove in a mortar, add fresh thyme, turmeric and hot pepper flakes. Ground all ingredients well.
Add balsamic cream, yogurt, dijon mustard and tomato sauce to the mortar. Mix well until all ingredients are well combined.
Cover the lamb shanks with the marinade and leave to marinate in the refrigerator for 12 hours or more. I can leave the meat to pickle for up to 48 hours. It makes it possible to prepare meat before baking for up to 2 days.
Peel the shallots, celery root and carrots. Cut into medium cubes.
Take the lamb shanks out of the fridge about 30 minutes before you start cooking so they come to room temperature.
Get a heavy baking dish, I use a clay dish. Put half the vegetables in the bottom of the dish, then add the lamb shanks, then add the remaining vegetables and a few sprigs of fresh thyme.
Preheat oven to 400F(200C).
Cover meat tightly with several sheets of aluminum foil. Cook in oven for 45 minutes at 400F(200C)Then reduce the temperature to 250F(120C) and cook for 3 hours, do not remove the foil!
Remove the lamb shanks from the oven and remove the foil, pour the sauce from the pan over the meat, increase the oven temperature to 350F (180C) and bake until golden brown, 8-10 minutes.