- Preheat the oven to Gas mark 4, 180°C, 350°F.
- Prepare the stuffing, heat half the butter in a large non-stick pan and cook the onion and mushrooms. Transfer to a large bowl and stir in the remaining ingredients.
- To make the braising sauce, heat the oil in the same frying pan, add the flour and cook for 1-2 minutes. Gradually add the stock, tomatoes, Tabasco (if used) and wine. Bring to the boil, reduce the heat, season and simmer for 5 minutes. Add the parsley, cover and set aside.
- Season the hearts and spoon the stuffing mixture into the cavity of each. Wrap with the bacon and secure with butcher's string. Heat the remaining butter in the same frying pan and brown the hearts on both sides. Transfer to a roasting dish.
- Pour over the sauce, cover and cook for 2 hours, or until the hearts are tender.
- Remove the butcher's string, slice and serve with creamy mash and seasonal vegetables.