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 2x3 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.
I cut it into narrow strips and served it (the first picture). It was much softer for having been marinated, but it still had a rather strong fishy smell and taste. This was more edible than the original. My wife’s comment was, “the fishy shoe leather is softer than before.” Even for me this is not something I would relish. A nice try but we will pass on "surume" next time.