This dish (which goes by many spellings) can be easily adapted to ingredients you have on hand. I like to serve the noodles and sauce with hard boiled egg and some chopped kimchi and shredded cucumber, although other vegetables can be used instead. If you want to make the dish a little more substantial, add some leftover plainly cooked beef or chicken. I love the chewy, slippery texture of sweet potato noodles, but if you like, substitute buckwheat noodles.
Gochujang (Korean red pepper paste) and sweet potato noodles are sold in the Korean section of supermarkets, where you can also buy the kimchi and banchan (side dishes) to serve with the dish.
Put the eggs in a small saucepan and add cold water to cover them by 1cm (7/16in). Place the pan over a medium flame. Bring to the boil then cover the pan with the lid, remove from the heat and leave for 10 minutes.
Drain the eggs and rinse thoroughly with cold running water. Crack the shells all over, then leave the eggs in a pan of ice water while preparing the other ingredients.
Bring a large pot of water to the boil, add the sweet potato noodles and cook until tender but still chewy, about five minutes. Drain the noodles in a colander then rinse under cool running water water, mixing and rubbing them with your hands until they no longer feel slimy. Leave them in a pan of ice water while preparing the other ingredients. (If using buckwheat noodles, boil them until al dente then drain, rinse with cold water and drain again.)
Make the sauce. Mix the gochujang with the corn syrup to form a smooth paste. Mix in the soy sauce, sesame oil, vinegar and sugar, then taste the sauce and adjust the seasonings as necessary.
Squeeze the kimchi with your hands to remove most of the liquid. Roughly chop the kimchi and finely julienne the cucumber.
Drain the noodles and divide them between four bowls. Put some of the chopped kimchi and shredded cucumber into each portion, then add a large spoonful of the sauce.
Remove the shells from the hard-boiled eggs and cut them in half. Place half an egg over each bowl of noodles.
Add the optional ingredients, then sprinkle with sesame seeds. Let each diner mix the ingredients together, adding more sauce if necessary so it lightly coats the noodles. (Leftover sauce keeps in the fridge for at least a week.) Serve with the kimchi and banchan.