Mix red pepper flakes, soy sauce, minced garlic, sesame oil, sugar, sesame seeds, and black pepper to create the seasoning sauce.

Slice the onion and carrot thinly, and chop the green onion.

Combine the sliced onion, carrot, and chopped green onion with the prepared seasoning sauce in a large bowl.

Prepare the perilla leaves by washing and drying them, then trimming the edges.

Layer the perilla leaves in a microwave-safe container, adding a spoonful of seasoning sauce between each layer.

Cover the container with plastic wrap or a lid and microwave for 2 minutes.