Fill a mixing bowl with cold water. Mix-in a handful of salt with the water. Add the cockles in. Then cover the bowl with some aluminum foil. Let the clams sit in darkness for at least 30 minutes. After 30 minutes, drain the water. Then, give the cockles a thorough rinse and scrub under running water.
Boil the Cockles
Bring a large pot of water up to boil. When it comes to a roaring boil, add in your cockles. (Set a timer for 3.5 minutes.) Use a wooden spoon and stir the cockles in one direction (this helps the meat stick to one side of the shell). After 3.5 minutes, sample one of the clams and see if it is fully cooked through. If it's not, let it boil for just a bit longer. IMPORTANT: If they are fully cooked, don't drain the pot just yet. Use a soup ladle and take out one scoop of the broth. Set it aside for later - we'll use this broth when making the cockle marinade. Now drain the broth and move the cooked cockles to a large mixing bowl.
Take the shells off each cockle. I would recommend doing this over a small mixing bowl - that way you can collect some more delicious broth. Note: For shells that don't open easily, use your spoon and pop the back of the shell (reference video). You want enough meat to fill 1 cup.
Make Soy Sauce Marinade
Throughly mix-in Soy Sauce (3T), Mirim (1T), Maesil (1T), Minced Garlic (1/2T), Cockle Broth (2T). Give it a good stir. Then add in 4-5 shakes of Sesame Seeds. Stir everything together
Prep Fresh Greens for Cockle Marinade
Dice your green onion (5 stalks) into small pieces. Then dice your 2 chili peppers into small pieces as well.
Season the Cockles
Take out another mixing bowl. Add in 1 cup of cooked cockles. Then add in the chopped green onions and chili peppers. Next, add in the gochugaru (1T). Then add-in 1/3 of the Soy Sauce Marinade you made - don't add everything at once! Give it all a good mix - feel free to add more Soy Sauce Marinade or Gochugaru if you need. Finally, finish it off with 1T of Sesame Oil. Give it a final mix.
Scoop out 2/3 of the seasoned cockles and place it to one-side of your plate. Leave the other 1/3 of the marinated cockles in the mixing bowl. Now, add freshly cooked rice (1.5 cups) into the mixing bowl. Mix until the rice is evenly coated in the marinade. Give the rice a taste. Next, we added 1 additional spoonfuls of the Soy Sauce Marinade into the rice. Feel free to do the same if you'd like. Finally, finish the rice with a drizzle of sesame oil. Give it a final mix!
Add the mixed rice (bibimbap) to the other side of the plate. Garnish with a few shakes of sesames seeds and sliced green onions. Bon Appetit!