Chop the cabbage into irregular 1-inch pieces.
Add the cabbage and the shio kombu to a ziploc bag. Zip the bag closed, but leave a good amount of air in the bag.
Shake the bag to distribute the shio kombu across all of the cabbage and massage the cabbage. Continue shaking and massaging for three to five minutes. Once the cabbage begins to release some moisture and starts to darken in color, you're finished with this step. Remove excess air from the ziploc bag, but keep the cabbage in the bag. Store the cabbage in the fridge for 25 minutes.
To serve, place the cabbage on a serving plate and top with crumbled nori.