Start by bringing a medium saucepan of water to a rolling boil. Carefully add medium eggs to the boiling water, ensuring they are submerged. Allow them to cook for about 6 minutes for a jammy yolk consistency. Once the time is up, remove the eggs and transfer them immediately to an ice bath.

While the eggs are cooling, gather a mixing bowl and whisk together your soy sauce, minced garlic, chopped chili peppers, brown sugar, and sesame oil. Mix thoroughly until the sugar dissolves and the marinade is well-combined.

After about 5-10 minutes in the ice bath, take each egg out and gently tap them on a hard surface to crack the shell. Under running water, peel the eggs carefully.

Place the peeled eggs in an airtight container and pour the prepared marinade over them, ensuring they are fully submerged. Seal the container tightly and refrigerate for at least 6 hours, or ideally overnight.

When ready to serve, take the marinated eggs out of the fridge and slice them in half to reveal the beautifully jammy yolk. Garnish with chopped green onions and sprinkle with sesame seeds if desired.