Question: how do you cook a jellyfish?
Answer: To prep jellyfish:
Rinse very well in cold water and drain. ... 
Mix soy sauce, sesame oil, vinegar, and sugar in a small bowl.
Let sit 30 minutes.
Just before serving, garnish with sesame seeds.
You may heat this recipe if you like; just stir fry it in a wok about 3 minutes, but it is best served cold.