Heat the vegetable stock and simmer the beans together with the bean chew for about 25 minutes. Remove from heat and quickly stir in the mashed potatoes with a whisk.
Dice the pork belly (cut the Mettenden into slices) and leave it in a pan (fry the Mettenden with a little oil), add the diced onions. Fry together until lightly browned. Add to the soup. Chop the parsley and stir in as well. Bring to the boil again and season with salt and pepper.