7 large stalks celery
2" piece kombu
1/3 cup water
1 tbsp. kosher salt
2 tbsp. mirin
2 tbsp. sake
1/4 cup soy sauce
wasabi root, julienned
wash celery and cut the top and bottom off of the celery stalks. peel the celery by taking the hair off. cut each celery in half and then in half again so that you have 4 slices of each celery stalk. then cut into 2-3" length pieces. place the already cut celery into a large ziplock bag and add in the 1 tbsp. of salt. shake bag and set aside for 20 mins.
bring a large pot of water to a boil for blanching the celery. add in the celery and boil for 2-3 mins. then immediately transfer to an ice bath to stop the cooking. drain and add back into the ziplock bag.
cut the kombu into 1/4" pieces and soak in water for 10 mins. in a small pot add in 1/3 cup water and the soaked kombu. bring to a boil and then add in the mirin and sake. boil off the alcohol. cool. then add in the soy sauce and wasabi.
add in the the liquid from the pot, including the kombu, into the ziplock bag of celery. let stand 2 hours.
remove from the bag and transfer to a container, and chill in the fridge.