Press sauté on the instant pot and set the timer to 5 minutes.
Dry fry the coriander seeds, star anise, ginger, and licorice (if using), and stir for a minute so the spices release their aroma.
Add leek or onion, carrot, and celery. Cook for 3-5 minutes allowing them to soften slightly.
Pour in 2 cups of water to stop the cooking process, followed by another 2 cups.
Add the remaining spices, and put the chicken on top, breast side up then sprinkle with the salt.
Toss in the spent corn cob, apple and the remaining 2-3 cups of water.
Add the coriander or parsley on top, close the lid and set to pressure cook for 15 minutes.
Press cancel on the instant pot and allow the pressure to release naturally for 20 minutes. If the silver float valve is still raised after this time, manually release the remaining pressure by pressing the pressure release button.
Remove chicken and shred the meat with two forks. Keep the frame to make a second batch of chicken stock. You can keep this in the fridge for a day or two or in the freezer for longer if you'll be making stock in future.
Strain the liquid (which is now your chicken stock) through a colander into a large bowl. You can also line it with muslin or a nut milk bag if you want to ensure no debris comes through. I never bother with this. If you're having the soup now, take some of the strained carrot and the shiitake to add to it then discard the rest of the veg and spices.
Having the soup later? Pour the strained liquid into a large jar and keep in the fridge for up to 5 days. It will also keep in the freezer for several months. Store the chicken meat in an airtight container. It can be used in your soups or in other meals that call for cooked chicken.
To assemble the soup add some cooked rice noodles to a bowl, followed by some shredded chicken, reserved carrot and shiitake (chop this and discard the stem). Add a big handful of baby spinach or other veg on top then pour over a couple of ladles of hot broth. To season, pour in a little soy, mirin, and sriracha then top with sesame seeds or gomasio if you have them on hand.