Bring a pot of water to a boil. Once boiling, carefully add the eggs. Cook for 7½ minutes, then remove them and place in an ice bath to cool down.

In a small bowl, mix gochujang paste, mayonnaise, sesame oil, and brown sugar until well combined. Taste and adjust gochujang as desired.

Peel the cooled eggs, rinse off any shell pieces, and mash them in a medium bowl. Stir in the sauce mixture and season with salt and pepper.

To serve, toast the sourdough bread and spread with butter. Top with kimchi, then spoon the gochujang egg mixture over toast and sprinkle with sesame seeds and chives.