Rinse the bracken fern, discard the base, and cut into 5 cm lengths.
Put 1 teaspoon salt (not listed) into a pot of boiling water, add the bracken fern, starting by immersing the thick stems first, then add the rest of the stems after 30 seconds.
After about 3 minutes, drain, chill under cold water, then drain excess water.
Mince the tomato and onion, toss with the blanched bracken fern, then season with salt, kombu tea, and sesame oil to taste.