Rinse the parsley roots thoroughly, peel and make with salted water for about 15 min, take out and save a little bit of cooking water.
In a hand mixer finely grind the roots, add butter, chopped parsley and season with salt and freshly ground pepper. If the puree seems too solid, add a little more cooking water until it becomes creamy.
This puree is recommended as an excellent accompaniment, along with boiled potatoes, to all “blue” prepared local fish.