Soak cockles in water with 1 tbsp coarse salt for 30 minutes to remove impurities.

Rinse cockles under running water and boil them in a pot of boiling water for 10 minutes. Stir in one direction to help cockles open evenly.

Cool boiled cockles in cold water and remove the meat from the shells. Use a spoon to twist open stubborn shells.

Slice green onion into thin strips and soak in water for 10 minutes to reduce spiciness.

Drain cockle meat and green onion strips, ensuring both are free of excess water.

In a bowl, combine cockle meat, green onion, minced garlic, soy sauce, sesame oil, chili powder, and optional spring onion and sesame seeds.