Heat the oil in a large pan over a medium heat and cook the onion and celery for 8-10 mins until tender. Add the paprika and mustard, cook for 30 seconds more, then crumble in the stock cubes and add the ham along with 1 litre water. Bring to a simmer, then bubble gently for 10 mins.

Tip in the root vegetables and lentils, then season to taste and continue to bubble everything for another 5-10 mins until the stew is piping hot. Just before serving, stir in the parsley, then ladle into bowls and serve with crusty bread on the side for mopping up the stew.