Mix the braising liquid: In the Instant Pot, add water or broth, soy sauce, rice wine, brown sugar, doenjang, gochugaru (if using), garlic, ginger, onion, green onions, pear or apple, peppercorns, and bay leaves. Stir to combine.
Add the pork belly: Place the pork belly in the liquid, fat side up. The liquid should come at least halfway up the meat.
Pressure cook: Seal the lid and cook on High Pressure for 60 minutes for a whole piece (45–50 minutes if cut into large chunks).
Make sure the valve is set to Sealing.
Natural release: Let pressure release naturally for 15 minutes, then quick-release the rest.
Reduce the sauce: Carefully remove the pork to a cutting board. Switch the pot to Sauté and simmer the cooking liquid for 8–10 minutes to concentrate flavors. Skim excess fat if you like.
Optional crisp: For a lightly caramelized edge, pat the pork dry and sear it in a hot skillet for 1–2 minutes per side, or broil for 3–5 minutes.
Don’t overdo it; you want tender, not crunchy.
Make ssamjang: Stir together doenjang, gochujang, sesame oil, honey, minced garlic, and green onion until smooth.
Slice and serve: Slice pork belly into 1/4-inch pieces. Spoon a little reduced sauce over the slices. Serve with lettuce, perilla, rice, ssamjang, kimchi, and garnishes.