Peel the potatoes. Cut the leeks in rings and cook in salted water for 10 minutes together with the potatoes. Finely chop the herbs and mix them with the soft butter. Add pepper and salt to taste. Roll the butter in aluminum foil and let it solidify in the fridge (about 1 hour). Drain the potatoes and leeks and blend it. Add pepper and salt to taste. Let the butter melt in a non-stick pan and fry the fish for about 7 minutes. Serve wth the leeks puree. Finish with a slice of herb butter and shrimps.
Fresh From Belgium