When we travel, we always try to find the most authentic, the most local, the most off-the-beaten-path. After all, we want to experience the true essence of the place we're visiting, a place we may never set foot in again. What if the true essence of a place is something we'd never considered? Beyond the local cuisine, what do locals eat? What gets their pulse racing? Hint: it's not always their "native" food.
Just because we're in a given country doesn't mean there aren't incredibly worthwhile food experiences that lay entirely out of the realm of that place's "native cuisine". Think of it more as "local cuisine", things that are in demand and highly beloved in one place although they may not be "of" that place. For example, a will never forget a quiet pizza meal in Nara, Japan, a place I had heard a lot about and wanted to try although it certainly wasn't what most would think of as Japanese cuisine. Could I have that same experience in any other restaurant in the world? No, of course not, because that restaurant's setting, clientele, and specific menu could only be gotten there in that tiny Nara pizzeria. Similarly, one shouldn't be afraid of opting for American BBQ in Singapore, Thai in Brooklyn, or Bangladeshi in Japan.
In the year 2018, Seoul has a very strong burger game. I'd wager that Seoul has some of the best and most widely accessible burger experiences outside of the US. One of my absolute favorite burgers (and burger spots) is at Almighty Cheeseburger near Anguk Station in north-central Seoul. Nestled among the traditional hanok structures and narrow allies, you will find a not very attractive concrete structure that houses Almighty, a fast-food "concept" complete with it's own mascot and 90's/hip hop-influenced product design, opened in 2016 by the same folks who own Brooklyn, the Burger Joint, which is the OG of great Seoul burger places.
There are many reasons to go to Almighty whether it be their sinful candied pork belly, the addictive milkshakes, or the occasional McDonald's-style apple pies, but the reason I find myself going back is for the caramelized onion burger. Two very thin smashed patties are stuck together with Swiss cheese and coated with caramelized onions so soft they take on an almost figgy texture, sweet like jam but highly umami from the browning of the onions. This is not a huge burger by any means but the flavors are so concentrated that you will be satisfied after the 8 or so modest bites it takes to finish.
I'm not sure that I've ever seen a burger quite like this back from in the United States. Put the kimchi on hold for just one meal and try this caramelized onion burger while in Seoul.