Turn your oven broiler on high. Cut your ginger bulb in half.
Place the halved ginger bulb and onion on an oven-safe pan and broil until it gets a nice char (not burnt) then take them out
Meanwhile, toss the chicken into the instant pot. Fill water to about 3/4 of the way to the max fill line
Then, toss in the onion ends, celery, charred ginger and onions into the pot as well. Be sure to NOT go past the max fill line.
Turn the instant pot on.
Put the lid on, make sure it is on sealing mode. Press the Stock button and let it do it's magic
You can let it natural release, but I have no patience. So, I put a towel over the valve, turned it to venting mode, and step back until it depressurizes. This is a scary process and it will make loud hissing noises, but just be careful to not burn yourself.
After it is done depressurizing, take the lid off and season it with salt and pepper (MSG Optional) to taste.
As soon as it is cooled down completely, you can store it in the freezer for up to 3 months.