Heat a little oil in a large heavy based frying pan and brown the meat on all sides. Place in The slow cooker.
Heat about 2tbsp oil in the pan and add the celery and onions. Saute gently for 3 to 4 minutes until softened then add the garlic and cook for 1 minute.
Stir in the sugar, red wine vinegar, tomato puree and stock and bring to the boil. Reuse heat and simmer for a minute or so then pour over the pork.
Add the sultanas and peppers, cover and cook for 8 hours.
Remove the meat from the pot and transfer to a board or serving plate.
Skim off any excess fat from the sauce and serve the sauce separately or poured over the pork.
Serve with minted new pots and fresh seasonal veggies.
The pork loin we used in France had only a thin layer of fat and no skin. If you use a butcher you can ask him to prepare the meat this way for you. I tested mine with a classic English rolled loin joint including skin which worked well but did produce a lot of fat, but this can easily be skimmed off before serving. The skin made it harder to carve so It is easiest to remove the skin t before caving. To cook in a conventional oven Prepare as above and place in a casserole with a tight fitting lid. Cook in a preheated oven 180℃/ 160℃ fan/gas mark 4 for 2 - 3 hours.