Echoing some other sentiments here - it’s a good substitute for sriracha, a little more depth and a little less heat. IMO the best natural pairing is with pork. Something really great happens when gochujang and pork come together.
In terms of strictly Korean dishes:
One of my favorite Korean jigaes is the humble gochujang jigae. It’s a “stoup” with a gochujang base, with some kind of meat and potatoes and squash/zucchhini. The secret to making this taste really great is to add a little denjang to it as well. Really comforting.
One of my favorite stews is the dak dori tang. Spicy chicken stew. This is as tasty as it is easy - just boil some chicken parts along with gochujang, soy sauce, potatoes, and whatever else strikes your fancy and you get a quick and delicious stew that is perfect with a warm bowl of rice.
A Korean home favorite that no one outside Korea really talks about is a beef and gochujang banchan/condiment. Fry up a bunch of ground/minced beef and gochujang together. You can add some other ingredients like garlic, wine, sesame oil/seeds, soy, etc. It’s like a spicy meat sauce or chili that is so concentrated it becomes a condiment. In a pinch, a scoop of this over a bowl of rice is a meal for many Koreans.
Of course, my all time favorite dish of all time, dduk bokki - spicy rice cakes deserves a mention. Rice cakes in a sweet and spicy sauce…you can’t go wrong with that.
It’s also a really great in a bulgogi type application. Typically it will be used with pork to make a sweet and spicy marinade. It’s almost impossible not to love this stuff.
And that gives us a segway into marinades - it’s pretty fantastic on almost any marinade. I tend to only use marinades on chicken and pork (I like to let my beef stand alone usually). Add it to your BBQ sauce for chicken or pork, for example. Or make a gochujang mayo and put it on a burger. Or whatever you want.
It also plays well with Mexican ingredients. There’s no reason you can’t add some to your fajitas, or enchilada sauce, or taco meat. Why not throw some in posole or menudo. Or chili.