Buchimgae or jijimi or chijimi is a thin, savory pancake from Korea. It's similar to a Japanese okonomiyaki, but is a bit less complicated to make. (Also closely related is pajon, a pancake with lots of green onions.) It's basically a pancake-like batter holding together a lot of vegetables and other ingredients. It's a great way of using up leftovers, and holds up a lot better than okonomiyaki as a bento item I think. It makes a nice change from rice or bread based bentos.
Here are two batter recipes. One is a traditional one using wheat flour and beaten egg, the other one is a vegan and gluten-free variation. Use the one that suits your needs. The traditional one is a bit lighter and crispier, and the vegan one is denser.