Soak the seaweed noodles in cold water.
Thinly slice the cucumber.
Julienne the carrot and onion as well.
Blanch the soaked seaweed noodles briefly in boiling water, then rinse them in cold water.
Cook the somyeon noodles, rinse with cold water, and drain well.
Prepare the sauce by mixing gochujang (Korean chili paste), vinegar, sugar, soy sauce, sesame oil, minced garlic, and chili powder.
In a large bowl, combine the seaweed noodles, cucumber, carrot, onion, and somyeon noodles, then mix with the sauce.
Place on a plate and sprinkle with sesame seeds to finish.