Add the water, kombu and salt to a bowl and let it soak overnight.

When all the tomatoes are peeled, bring the pot of stock back up to a boil, then turn off the heat. Put the peeled tomatoes in the pot and cover with a lid. The tomatoes will gently poach in the liquid as it comes back down to room temperature. When it reaches room temperature, gently transfer the tomatoes to a container and pour the stock over them. Seal and refrigerate overnight to allow the tomatoes to absorb the flavor from the broth.

The next day, drain off 1 C of the poaching liquid from the tomatoes and pass it through a tea strainer into a small saucepan. Whisk in the cornstarch and soy sauce then bring to a boil. The sauce should become clear and thicken just a little (it will still be very loose). Put the pot in a water bath to bring the sauce back to room temperature then put it in the freezer to chill.

For the zucchini, bring a large pot of heavily salted water to a boil. Cut the top and bottom off of the zucchini then slice it lengthwise down the middle. Use a spoon to scrape any seeds out. Use a mandoline or a sharp knife to slice the zucchini into long noodles. Prepare a large bowl of ice water. When the pot of salted water reaches a rolling boil, add the zucchini and stir for a few seconds. The zucchini should be wilted but slightly crunchy still. Drain the "noodles", and dump them into the ice bath. Squeeze some of the excess water out of the noodles with your hands and transfer to a bowl. Refrigerate to chill.