1. Add the potatoes to a large saucepan and add water, a good pinch of salt and the white wine vinegar.
2. Place the potatoes over high heat and bring them to a boil. Cook them for 5 minutes. In the meantime chop the carrot. Add the carrot after 5 minutes to the potatoes.
3. Cook for another 5 minutes and then add the peas.
4. Then take the pan off the heat and leave the potatoes, carrots and peas in the pan for 2 more minutes to let the peas thaw. Then drain the vegetables. Add them back to the pan. Add the butter and milk. Season with a pinch of pepper and salt.
5. Mash the potatoes. Then cover the pan and put the mash aside until later. Then peel and chop the garlic clove and the yellow onion. Add both to a large non-stick pan together with the diced salted bacon.
6. Place the pan over medium-high heat and fry the onion, garlic and bacon in the melted bacon fat for 8 minutes. Stir regularly. Then add the sausages to the pan.
7. Pour in the balsamic vinegar, the warm stock and the red port. Season with a pinch of pepper.
8. Stir and cover the pan. Cook the sausages for another 8 to 10 minutes until cooked through (or like Keith says it: let the fuckers rock). In the meantime reheat the potato mash. Put the mash onto plates and top with the cooked sausage and the onion and bacon sauce. Serve hot.