Roughly chop the ginger, leaving the skin on.
Remove the skin from the onion and roughly chop.
With your Instant Pot set to sauté mode, high heat, add the spices (cinnamon, cloves, star anise, and fennel seeds), and toast them until fragrant. 3-5 minutes
Add the ginger and onion and continue to cook on sauté until they start to blacken. It’s ok if the spices begin to burn a little.
Turn the Instant Pot heat off and carefully pour in the water. It is going to spit and splash, so be extra careful.
Add the meat products to the water and the apple. Cover and set the cooker to high pressure for 1 hour.
When the hour is up, let the cooker rest pressurized for another 30 minutes.
Carefully release the pressure and remove the lid.
Strain away the solids from the stock using a colander.
Strain the stock once again using a fine mesh strainer or cheesecloth.
The meat will have given up most of its flavor at this point; however, I like to shred any beef or chicken I can and add those to my topping list for a little extra flavor and texture. Otherwise, you can use it for another purpose or discard it.
Stir in the fish stock and adjust salt and pepper as desired.
Your pho stock is now ready! You can use this immediately or refrigerate it for up to a week. It also freezes very well and can be stored frozen for up to 6 months.
If you are going ahead and eating the same day, boil water and prepare your noodles per package instructions.