Cut courgette in small cubes. Peel carrots and chop into finley strips with a potato peeler. Cook carrot strips in salted water until they have a slight bit, rinse with cold water and drain them. Heat oil in a covered pan, fry courgette cubes and carrot strips, season to taste with salt.
Mix milk and soup, bring to the boil, add cheese and melt it. Stir in butter and polenta. Simmer for approx. 7 minutes, stirring permanently. Season to taste with salt and pepper.
Fry the salted fish on both sides, spice with a bit of rosemary.