START: In a large bowl, whisk together the hoisin, honey, five-spice powder and 2 tbsp gochujang. Measure 3/4 cup of the mixture into a small bowl and stir in the remaining 3 tbsp gochujang and the ginger; set aside at room temperature if pressure cooking or cover and refrigerate if slow cooking. Add the rib sections to the remaining hoisin mixture in the large bowl and turn to coat. Place the steam rack in a 6-quart Instant Pot, then pour in 1 cup water. Arrange the ribs upright in a circle, with the meaty sides facing the walls of the pot.
Fast (Pressure Cook): Lock the lid in place and move the pressure valve to Sealing. Select Pressure Cook or Manual; make sure the pressure level is set to High. Set the cooking time for 25 minutes. When pressure cooking is complete, allow the pressure to reduce naturally for 15 minutes, then release the remaining steam by moving the pressure valve to Venting. Press Cancel, then carefully open the pot. Let cool for 5 minutes.
-OR-
Slow (Slow cooking) : Select More/High Sauté and bring the water to a boil. Press Cancel, lock the lid in place and move the pressure valve to Venting. Select Slow Cook and set the temperature to More/High. Set the cooking time for 8 to 9 hours; the ribs are done when a skewer inserted into the meat between the bones meets no resistance. Press Cancel, then carefully open the pot. Let cool for 5 minutes.
FINISH: While the ribs cool, heat the broiler with a rack about 6 inches from the element. Line a rimmed baking sheet with foil. Using tongs, carefully transfer the ribs meat side up to the prepared baking sheet. Generously brush with half of the reserved hoisin mixture and broil until the glaze begins to bubble, 2 to 3 minutes. Remove from the broiler, brush with the remaining mixture and continue to broil until bubbling, another 2 to 3 minutes. Cool for 5 minutes, then cut between the bones to separate into individual ribs. Transfer to a platter, then sprinkle with the cilantro, sesame seeds and scallions.