Beans soak in cold water for 4 hours.

Then boil in salted water for 1.5 - 2 hours.

Since the fern is kept in a salt form, it is first steeped for 4 hours, then cut into pieces and boil 10 minutes, drain off water. Onion cut into half rings, fry in vegetable oil until Golden brown. Put in onions, boiled fern and cooked beans, stir, add soy sauce, cover, simmer on low heat for 5 minutes. Ready!