Place cold large eggs in a saucepan, covering them with about an inch of cold water. Bring to a rapid boil over medium-high heat, then cover and remove from heat. Let sit for 12-14 minutes.

Prepare an ice bath in a large bowl by filling it with cold water and ice.

Transfer boiled eggs to the ice bath using a slotted spoon. Allow them to cool for about 10 minutes.

Gently crack the shells and peel the eggs under cold running water.

Slice each egg in half lengthwise and carefully remove the yolks into a mixing bowl.

Add mayonnaise, gochujang, rice vinegar, sesame oil, garlic powder, onion powder, and black pepper to the yolks.

Mix the yolk mixture until smooth and creamy; adjust seasonings as needed.

Spoon the creamy filling back into the egg whites, using a piping bag for a professional finish.

Garnish with sliced green onions and sesame seeds; add gochugaru if desired.

Refrigerate for at least 30 minutes before serving.