Pour two bottles of good quality red wine into a large pot.

Bring the wine to a simmer and reduce it until it becomes sweet and syrupy, with very little tannin left. It should resemble a concentrated wine syrup.

Dredge the short ribs in flour, then add vegetable oil to a hot Dutch oven. Carefully place the short ribs in the pot.

Sear the short ribs slowly on all sides until they develop a deep, golden-brown crust. Avoid burning them, as this can make the final sauce bitter.

Once seared, remove the short ribs from the pot and set them aside on a tray.

In the same pot, add sliced shallots and caramelize them until they are a beautiful golden color to add sweetness to the dish.

Add the rest of the chopped vegetables (carrots, celery, leek, garlic) to the pot and cook, stirring occasionally. Scrape the bottom to prevent any black bits from forming.

Stir in the tomato puree and cook for a minute.

Return the seared short ribs to the pot and turn off the heat to prevent burning the bottom while you add the liquids.

Pour in the reduced red wine, followed by the beef stock, bay leaves, and thyme sprig.

Cover the contents of the pot with a piece of parchment paper cut into a circle (a cartouche) and then place the lid on.

Braise in a preheated oven at 140°C (275°F) for 3.5 to 4 hours, until the meat is fork-tender.

Once cooked, remove from the oven and let the ribs rest in the braising liquid for at least 45 minutes. This helps the meat reabsorb moisture.

Carefully remove the meat and strain the sauce into a clean pan. Reduce the sauce over medium heat until it thickens and becomes a glaze. Finish the sauce with mustard and vinegar, and season to taste.

Peel and chop the celeriac and potatoes. Place them in a pot and cover with milk. Simmer gently until the vegetables are very tender.

Transfer the cooked vegetables and a little of the milk to a blender. Add butter and blend until completely smooth. Season with salt.

Spoon a generous amount of celeriac purée onto a plate. Place a short rib on top and generously spoon the glossy red wine glaze over the meat.