11. Prepare the blue crabs: Thoroughly clean the blue crabs under cold running water using a brush. Remove the apron (triangular flap) from the underside of each blue crab. Carefully pry open the top shell (carapace) from the body. Discard the gills and any internal organs that are not roe or tomalley. Cut each blue crab body into 2-4 pieces, depending on size. Keep the top shells for serving.
22. Prepare the Ganjang Gejang Marinade: In a large pot, combine 500g soy sauce, water, 50g sugar, soju, 30g garlic cloves, 20g ginger, dried red chili, Korean radish, 100g onion, 50g scallion, kelp, dried shiitake mushrooms, jujube, ginseng, and whole black peppercorns. Bring the mixture to a boil over medium-high heat, then reduce heat and simmer for 15 minutes. Remove from heat and let the Ganjang Gejang marinade cool completely to room temperature. Strain the cooled marinade, discarding the solids.
33. Marinate the Ganjang Gejang: Place half of the prepared blue crab pieces into a clean, airtight container. Pour the cooled and strained Ganjang Gejang marinade over the blue crabs, ensuring they are fully submerged. Close the container tightly and refrigerate for at least 2-3 days before serving. Turn the blue crabs occasionally to ensure even marination.
