Place the flour in a medium-sized bowl. Lightly season the veal osso buco with salt, then dust in flour, shaking off any excess.
To chop the vegetables for the ‘soffritto’ (sautéed-base flavouring): add the onion, celery and one of the carrots (roughly chopped) into the bowl of a food processor. Mix until finely chopped. Alternatively, use a sharp knife to finely chop the onion, celery and one of the carrots.
Heat half of the olive oil in a large heavy-based stockpot (preferably cast iron) over medium heat. Cook the veal osso buco for 2-3 minutes on each side until the veal is browned all over. Remove veal from the stockpot and transfer to a plate.
To make the soffritto, heat the remaining olive oil in the stockpot over medium heat. Add the finely chopped vegetables, chopped rosemary and bay leaf. Cook for 2 minutes, stirring from time to time. Add tomato paste to the soffritto and cook, stirring almost continuously for 3 minutes.
Add the white wine and simmer, stirring from time to time for 5 minutes to reduce slightly. Pour the beef stock into the wine and vegetable liquid. Stir to combine. Return the osso buco to the stockpot in a single layer, if possible. Chop the remaining carrot to a thickness of 1.5cm and add to the stockpot with veal osso buco.
Reduce the heat to low. Cover and simmer for 30 minutes.
Use tongs to carefully turn the osso buco and ensure that no meat is stuck to the bottom. Cook for 30 minutes over low heat.
Add potatoes around the osso buco and cook for a further 30 minutes or until the osso buco is tender. From time to time, check the amount of liquid in the pot. Add a little more water, if required. Discard the bay leaf before serving – buon appetito!