After you get all the ingredients, you need to soak four inches of dry seaweed in cold water before cooking - anywhere from one minute to overnight. When you finished soaking seaweed, you chop it into bite size pieces. You also need to clean and cut off the roots of green onions, then chop them to get one teaspoon. After that, you slice mushroom into thin slices, and cut the tofu into small cubes for one teaspoon.