Sear Short Ribs: Season 6 bone-in beef short ribs with kosher salt & ground black pepper. Bring a large cast iron skillet to a medium-high heat, add 1 tablespoon butter to melt. Once hot, sear the short ribs on all sides.
Crockpot: Place the short ribs in the slow cooker with 2 cups Korean BBQ Sauce. Let cook on the LOW setting for 6-7 hours or HIGH setting for 4-5 hours.
Toppings: Shortly before the short ribs are done cooking, prepare any toppings that you will be serving with the tacos.
Shred + Serve: Remove the cooked short ribs from the slow cooker and shred the meat with 2 forks, discard bones. Feel free to return the meat back to the slow cooker if you want it more juicy when serving. On each tortilla, smash some avocado, add some shredded beef, and top with quick pickled onions, ½ cup spicy mayo, ½ cup feta cheese, ¼ cup fresh cilantro, and an extra drizzle of Korean BBQ Sauce, if desired!