Peel and finely chop the onion. Wash the carrots, scrape off a little with a knife and cut lengthways into thin strips approx. 10 cm long. Cut the mustard pickles into small pieces.
Briefly sauté the onion cubes in hot butter, add the carrot strips and sauté briefly. Pour in the vegetable stock and stew for about 7-10 minutes so that the carrot strips are still firm to the bite. Add the mustard cucumber and crème fraîche or sour cream, season with salt and pepper and, if necessary, horseradish or mustard. Mix in freshly chopped herbs before serving.
Serve with fish with wild rice mixture or small jacket potatoes.