Cut the soft tofu into bite-sized pieces.
Boil the chewy noodles in boiling water for 4 minutes, then rinse them in cold water.
Make the sauce (gochujang, soy sauce, minced garlic, sugar, vinegar, sesame oil).
Heat cooking oil in a pan and stir-fry sliced onion and green onion.
Add the boiled noodles and sauce to the pan and stir-fry together.
Add the soft tofu and gently mix on low heat for 2 minutes.
Transfer to a bowl and finish by sprinkling sesame seeds and sesame oil.