For the sauerkraut, heat the oil in a pan over a medium–high heat. Fry the onion, stirring constantly, until soft and translucent. Add the cabbage, cider, vinegar, 100ml/3½fl oz water, salt and caraway seeds and bring to a boil. Cover and reduce the heat, then simmer for 45 minutes, or until the cabbage is tender. Keep an eye on it, if it looks as though it’s drying out too much, add a little water.
For the pork, put the bacon in a saucepan and cover with cold water. Stud the onion with the cloves and add to the pan with the dark brown sugar, bay leaves, peppercorns, chilli flakes and cider. Cover the pot and bring the water up to the boil. Skim off any scum that comes to the surface, then turn down the heat and simmer for 45–60 minutes, or until the meat is cooked and tender. Lift out of the cooking liquor using a slotted spoon and slice into about six to eight long rashers/slices
For the split pea purée, rinse the split peas under running water. Heat 2–3 tablespoons of the rapeseed oil in a large saucepan. Add the onion and garlic and gently fry until soft and translucent. Add the split peas. Pour in 1.2 litres/2 pints water, bring to the boil and skim off any white scum that appears on the surface. Turn the heat down and simmer gently with a lid on the pan for 45–60 minutes, or until the split peas are thick and mushy. Add the remaining rapeseed oil and the lemon juice and transfer the mixture to a food processor, or use a stick blender to purée. Season with salt and pepper. (This can be made in advance. If it thickens on standing, reheat with a little extra water.)
Serve the split pea purée and sauerkraut with rashers of pork belly.