Preheat the oven to 200°C/180°C fan/Gas 6.
Place a large casserole over a high heat. Brush the sausages lightly with 1 tablespoon of the oil and add to the heated casserole. Sear the sausages, turning regularly to brown them. Remove from the casserole and set aside on a plate and cover with tinfoil to keep warm.
Meanwhile, you need to peel the tomatoes. To do this, bring a pot of water to the boil, then reduce the heat to a simmer. Have a bowl of iced water on the side. Remove the core of each tomato by inserting a small knife into the tomato at a slight angle, just deep enough to remove the core, and cutting in a circle. Then cut a small X in the bottom of the tomato. Carefully place the tomatoes in the pot of simmering water. Once the skin begins to lift away from the X, remove the tomatoes with a slotted spoon and place in the bowl of iced water. Once the tomatoes are cool, the skin will peel off easily and you can finely chop them.
Add the remaining tablespoon of oil to the casserole and lower the heat to medium. Add the onions, carrots, celery and garlic. Sweat for 5 minutes, until soft, stirring all the time. Don’t allow them to colour.
Add the wine and scrape the bottom of the casserole to release all the caramelised bits. Increase the heat and reduce the wine to half its initial volume.
Add the tinned and fresh tomatoes, the bouquet garni and the water. Stir well and season with salt and pepper. Add the beans and the sausages and cover with the lid, then cook in the oven for 45 minutes.
Remove the casserole from the oven. Remove the bouquet garni and leave to rest for 15 minutes before serving. Garnish with some chopped fresh flat-leaf parsley.