Cut any fat off the hearts and soak them in cold water to remove any blood. Then cut the hearts in half and remove arteries and fat.

Cut the bacon into strips 5 mm (1/4 in) wide and use to spike the hearts.

Dice the onion.

Fry the onion and hearts in the oil in a large, heavy-based saucepan until the meat is browned all over. Add the stock, salt and pepper to taste and the paprika, cayenne and bay leaf. Cover the pan and braise the hearts for 1 1/2 hours.

Scrape the carrots and quarter them lengthways. Slice the leek and celery. Peel and coarsely dice the celeriac.

Add the prepared vegetables to the pan 25 minutes before the end of the cooking time. Wash the tomatoes, cut into wedges and cook them with the hearts for the last 10 minutes of the cooking time.

Thicken the sauce with the tomato puree and the cornflour dissolved in a little cold water. Bring to the boil once and stir in the cream.