Brush whelks and rinse under cold water with coarse salt (30g / L).
During this time, slice a green leek, one onion, 1/2 fennel and place in a saucepan with water, peppercorns, fennel seeds and parsley stem.
Cook for 20-30 minutes depending on the whelks size. Remove the operculum and eat with mayo or steamed leeks.