Melt the butter in a saucepan.
Add the onion and fry for 2 minutes.
Add the remaining vegetables, the pulped tomato and the herbs and sauté for another 4-5 minutes. Add the stock and simmer for around 15 minutes until the potatoes have softened.
Take the red fish and cut it into fillets with a sharp knife and then cut into cubes. Place the fish in the soup and let it boil for around 15 minutes.
Finally, add the fresh cream and stir.
Garnish with the dill and serve.