Wash the fish, pat dry and cut into cubes. Drizzle with the lemon juice. Clean the carrot and leek and cut into strips and cut the cauliflower into small florets.
Fry the onion cubes in the oil until translucent, add the other vegetables and stir-fry for 5 minutes. Pour in the broth and season with salt and pepper. Add the fish and let everything simmer over low heat for about 15 minutes.
Finally sprinkle with finely chopped parsley and dill.