Heat the oil in a deep frying pan with a lid. Add the sausages and cook, turning them, until they are brown. Lift from the pan, then add the onion and garlic. Cook, stirring, for 5-8 mins until softened – add a splash of water if the onion starts to colour too much before it softens.
Add the fennel seeds and cook for a few mins until toasted. Pour in the beans and their liquid, plus half a can of water. Add the tomato purée, stock, celery, vinegar and honey, then cover and leave to cook for 12 mins. Add the sausages and cook until warmed through, then stir through the parsley.