The year I lived in Kyoto, Japan, I traveled to Korea over winter break. On Christmas morning, in the freezing cold, I was walking to catch a bus and came upon a street food vendor making breakfast sandwiches. The snow had begun to fall and he let me shelter under his tarp while he made me a very simple cabbage-egg omelet that he served between big fluffy slices of white bread with a delicious sauce that reminded me of Japanese okonomiyaki sauce. I loved the sandwich so much! It felt vaguely healthy but also rich and satisfying. When we made our own yakisoba sauce, with some of those same flavor notes, I knew I wanted to try to recreate this breakfast sandwich.