Preheat the oven to 180°C/350°F.
Prepare veal: Rub the meat dry with a kitchen towel. Sprinkle it with salt, pepper, and thyme, and rub it well.
Prepare vegetables: Chop the onions and the garlic and set them aside. Chop the celery, tomatoes, and carrots and set them aside in a separate bowl.
Sear the meat: Heat the oil in a Dutch oven. Sear the veal all over, about 3 minutes per side. Don’t forget to sear the sides of the meat as well.
Add onions and garlic and cook them for about 2 minutes, stirring. Add celery, tomatoes, and carrots, and cook for another 3 minutes.
Roast: Add the chicken stock and ½ teaspoon of fine sea salt. Bring to a gentle boil and cover. Place the Dutch oven in the oven and cook for 1 ¼ to 1 ½ hours until the internal temperature reaches 72°C/ 160°F.
Rest: Remove the veal from the pot and let it rest while you finish the sauce.
Sauce: Add a little white balsamic to the vegetables. Blend the sauce until smooth.
Adjust the taste with more salt, black pepper, and more vinegar if required.
Slice the roast and serve immediately with the sauce.