Remove the sausages from their skins and break up into small pieces. Heat the oil in a frying pan and fry the onion and sausages until the onion has softened and the sausages are golden. Stir in the garlic, then cook for 1 min before adding the tomatoes, tomato purée, kidney beans and chilli powder. Bring to the boil and cook for about 10 mins until thickened.
Split the rolls down the middle and toast the cut sides on a griddle pan. Spoon the hot sausage chilli into the rolls and finish with the cheese. Serve with potato wedges, if you like.