1 medium onion, ¼- ½ a root of celeriac, 2 medium carrots, 2 small or one large leek, and a small bunch of parsley. Cut into small dice or slices. add about 200g green lentils, 2 tblsp tomato paste and two medium sized diced potatoes. Cook all in stock until soft then mash a little. Reheat, adding frankfurters at this stage.