Korean Street Toast (Gilgeori-toast 길거리토스트). It's basically a Korean breakfast sandwich. There's no one way to make it but it's usually egg mixed with various veggies that is fried into a patty and put on buttered toast (think made like a grilled cheese). It's gotten super popular in Korea as a quick street food breakfast and there's Korean Toast shops popping up all around the world now. Here's a recipe from Maangchi, but you can put basically anything you want on it. This one had ham, cheese, and a sweet gochujang sauce on it. Got it from a vendor in a local Korean themed food hall.
I make similar sandwiches at home for breakfast. I was inspired by the Korean breakfast toasters specifically. They are easy to make and delicious.
I've made a somewhat similar breakfast sandwich my whole life only because my dad was fond of it:
It's basically an egg salad sandwich on toast. Just brown up some Jimmy Dean breakfast sausage and mix in egg and scramble it all together. Take it off the heat and mix in mayo. Then put on toast with a slice of American cheese. Super simple but so delicious.