Wash the perilla leaves thoroughly and remove excess water.
Mix soy milk, soy sauce, vinegar, and sugar to make a cold broth.
Cook somyeon noodles in boiling water, rinse in cold water, and drain well.
Place the noodles in a bowl, add perilla leaves on top, and pour in the cold soy broth.
Top with sesame seeds and finely chopped cucumber as garnish.