Cook the buckwheat noodles, rinse under cold water, and drain.
Julienne the cucumber, carrot, and red cabbage.
Place the cooked buckwheat noodles and the vegetables in a bowl.
Mix perilla oil, soy sauce, vinegar, sugar, minced garlic, and sesame seeds to make the sauce.
Pour the sauce over the noodles and salad, then toss lightly.