Fill a medium saucepan with water and bring it to a gentle boil over medium heat. Carefully lower the eggs into the boiling water and cook for 6 minutes.

In a mixing bowl, whisk together the soy sauce, minced garlic, sesame oil, brown sugar, and chili flakes until well combined.

Transfer the eggs to an ice bath for about 5 minutes to cool them down. Then, gently peel under running water.

Place the peeled eggs in a container and pour the marinade over them. Ensure they're fully submerged. Cover and refrigerate for a minimum of 6 hours.

Once marinated, slice each egg in half and serve with sesame seeds and sliced green onions.