Boil the chicken breast, let it cool, and shred it along the grain.
Slice cucumber and onion thinly.
Cook the wheat noodles (somen), rinse them in cold water, and drain well.
Prepare the sauce (gochujang, vinegar, soy sauce, minced garlic, oligosaccharide, sesame oil, and sesame seeds).
Place the noodles, shredded chicken breast, and vegetables in a cold noodle bowl, then add the sauce.
Mix thoroughly and serve.