Drain the oil from the tuna using a sieve.
Finely chop the onion, green onion, and Cheongyang chili pepper.
In a bowl, mix the tuna, doenjang (fermented soybean paste), gochujang (Korean chili paste), minced garlic, and all chopped vegetables together.
Add sesame oil and toasted sesame seeds, and mix once more.
Wrap with lettuce and enjoy.