Marinade: Sake, water, mirin, soy sauce in equal amounts. (The original recipe called for sugar but I did not add any sugar). I put the mixture in a sauce pan and let it come to a boil and reduced the heat. I let it simmer for another 1 minute. When the marinade cooled down to room temperature, I added a 2×3 inch dried kelp. After the kelp rehydrated, I put the dried surum squid in a sealable container and put the kelp on the top of the squid. I marinated it for 3 days in the refrigerator (see the picture below).
Before I served it, I removed the excess moisture and grilled it in the toaster oven briefly.