We rinse the knees, dry them, salt them, and pepper them. We clean the vegetables and onion, cut them into cubes, and place them with the knees in an enameled GN 1/1 100mm deep pan. We drizzle with oil. We place in a preheated oven and roast until colored. Then we pour water over the knees and vegetables, add a sprig of rosemary, and braise (or bake) in a combi mode at 130°C / 80% steam for about 2 hours. During braising, we baste the knees with the liquid and add water as needed. We remove the soft knees, thicken the liquid with a roux, reduce it, season, and strain through a fine sieve. When serving, we sauté fresh root vegetables in butter. We pour the sauce over the knee and arrange the vegetables around it.