Sweat fine leek and carrot strips in the mixture of margarine and oil, add a little crushed garlic and grated lemon zest, stir in the tomato paste, sweat for a short time, dust the mixture with flour and fill up with the stock. Bring everything to the boil and add coarse cubes of fish fillets, seasoned with salt and garlic and drizzled with lemon juice. Let these cubes simmer at the beginning (do not boil) and improve the ragout with sour cream before serving.
As a side dish boiled potatoes or rice and celery salad with raisins soaked in rum.