Clean cockles thoroughly by rubbing them hard in water to remove any debris.

Place cleaned cockles in weak salted water for 3 hours to help them purge sand.

Prepare the seasoning sauce by mixing soy sauce, minced green onion, minced garlic, red pepper powder, sesame seed powder, and sesame oil in a bowl.

Cut red pepper threads into approximately 3/4-inch pieces.

Bring water to a boil and gently drop cockles into the boiling water for 2 minutes.

Remove the cooked cockles from the water and discard any empty shells.

Arrange the remaining shells with cockle meat on a heat-proof dish.

Sprinkle the prepared seasoning sauce evenly over the cockles on the dish.