Place the dried gosari / fernbrake in a large bowl and immerse in water overnight (8 to 12 hours). Drain away the water. Boil some water in a sauce pan (enough to cover the fernbrake) and add the fernbrake in rolling boiling water then boil for a further 30 minutes. Drain away the water and rinse the gosari well under cold running water.
Comb through the fernbrake and cut any hard woody bits from the stem and discard them. (This is a bit of a fiddly and time consuming process but is totally worth it!) Line them up and cut into index finger lengths. Transfer them into a mixing bowl. Add the seasoning sauce and mix them well.
Heat up a skillet over medium high heat. Once heated, spread the cooking oil. Add the seasoned fernbrake and stir around for a few minutes. Add the water (3 Tbsp) and simmer it over low heat for a further 3 minutes. Garnish with the sesame seeds. Remove from the heat. Serve. It can be refrigerated in an air tight container for 3 to 4 days.
*1 Tbsp = 15 ml**The prep time does not include overnight soaking of dried gosari (fernbrake)