From cookinglight. Chapchae is a Korean noodle dish. I think you can substitute the steak with other meats or seafood--it's mostly to add a little meaty flavor. * I use the sweet potato noodles for more authenticity in place of the bean thread noodles (I boil them for 5 minutes then rinse with cold water thoroughly). It takes a while to make this but it's really authentic and flavorful.