Fry the onions and sausage for a few more minutes ... then add to the simmering broth. Add as much cabbage as the broth will support - if you want heavy soup add loads of greens, if lighter ...
For the sausage casserole, heat the vegetable oil ... Slice the inner Savoy cabbage leaves (from the pesto ingredients) and stir them into the stew. Stir well and bring the mixture to the boil ...