Wash the perilla leaves and cucumber thoroughly, then slice them into thin strips.
Remove excess moisture from the cold tofu and cut into bite-sized pieces.
Cook the wheat noodles, rinse in cold water, and drain thoroughly.
Mix the sauce ingredients (soy sauce, vinegar, sesame oil, chili powder, minced garlic, sugar) together.
Place the noodles, tofu, cucumber, and perilla leaves in a bowl, and drizzle with the sauce.
Sprinkle toasted sesame seeds on top to finish.