Dice the onion and potato, cut the whelks in bite size pieces.
Drizzle some oil in a cooking pot, add the diced onion and cook on medium heat until translucent. Add the clam juice, whelks, water, dashi, fish sauce and potatoes.
Simmer until the potatoes are just about to be done, then add the corn and the slurry little by little, until desired consistency (I like mine very thick). Be sure to mix right after pouring some slurry to avoid clumps.
Once the desired consistency is achieved, remove from the heat and add the pepper and the cream, and mix. Add salt if needed. Serve. If you feel fancy, you can add a little bit of parsley in the bowl.