Preheat the oven to 190C/375F/Gas 5.
Place the pork belly, skin-side up, onto a roasting rack. Stab all over with a roasting fork or sharp knife. Season all over with salt and freshly ground black pepper.
Roast the pork belly in the oven for approximately two hours, or until tender and cooked through. Remove from the oven, cover, and set aside to rest on a warm plate.
Add the shallot to the juices in the roasting tray and place the tray over a low to medium heat, stirring to coat the onions in the liquid. When the onions have softened, add the capers and apple juice and increase the heat until the liquid is bubbling. Continue to cook until the liquid has reduced to a sticky sauce.
Stir in the diced apple, shrimps, chopped herbs, cream and butter until well combined.
When the pork has rested, carve it into thick slices.
To serve, divide the pork slices equally among four serving plates. Spoon the shrimp-and-apple sauce all over the meat. Spoon a dollop of mashed potato and a heap of summer cabbage alongside each serving.