Cut the squid and pork belly into bite-sized pieces.
Slice the onion, green onion, and Cheongyang chili pepper.
In a bowl, make the marinade sauce by mixing gochujang, red pepper powder, soy sauce, sugar, garlic, ginger, sesame oil, and pepper.
Marinate the squid and pork belly in the sauce for 10 minutes.
Heat a pan over high heat, add oil, and stir-fry the marinated ingredients.
Add the vegetables and stir-fry together.
Stir-fry quickly over high heat to add a smoky flavor and finish.