Add the cubed pork to the instapot, sprinkle with salt and add 3/4 cup water. Close lid and turn instapot setting to meat for 30 minutes
About 10-15 minutes before instapot pork is done, start the onion-spice mixture. Add oil to a large skillet and turn to med-high heat. Add chopped onion and saute for about 5 minutes or until caramelized. Add mashed garlic and cook 30 seconds. Add all spices (through pepper) and stir into onion mixture for 30 seconds to toast and blend.
Add vinegar to hot skillet mixture. Add quince paste and melt into the onion mixture, stirring in thoroughly.
When instapot pork is done, open and remove liquid (pork juices and water) from bottom of instapot and add to onion mixture in skillet over med-high heat. Add pork chunks and stir thoroughly, coating pork cubes with onion-spice mixture.
Serve in low carb tortillas with pickled onions and cilantro garnish.