In a saucepan with a thick bottom, lightly fry the onion and carrot in a small amount of vegetable oil. Add the potatoes, cut into small cubes, mix, leave on low heat for a couple of minutes.
Pour the contents of the pan with broth (vegetable, chicken or just boiling water). Bring to a boil over high heat, reduce the heat to medium and cook for about 10 minutes until the potatoes are ready.
Then add the fish to the pan, cook for about 5 minutes.