Season the ribs with salt, black pepper, and brown sugar on both sides.
Make the marinade by mixing soy sauce, honey, sesame oil, red chili paste, white onion, garlic, ginger, green onion, and red pepper flakes.
Place the ribs in a large zip top bag, add the marinade, and refrigerate for at least 4 hours.
Prepare the smoker to 250-275°F and add hickory wood chunks.
Place the ribs meat-side up on the smoker and cook for 3 hours.
Wrap the ribs in aluminum foil and continue cooking for 1-2 hours until tender.
Make the Korean BBQ sauce by melting butter in a saucepan, adding onion and garlic, and cooking for 1-2 minutes.
Add soy sauce, water, vinegar, sesame oil, chili paste, and brown sugar to the saucepan and stir to combine.
Add ginger, black pepper, and red pepper flakes, then make a corn starch slurry and add it to the sauce to thicken.
Unwrap the ribs, brush them with the Korean BBQ sauce, and cook for an additional 20-30 minutes until the sauce is tacky.
Cut the ribs into 1-2 bone pieces and serve.
