Place vegetable scraps in a stainless-steel basket. If you don't have a basket, place in the Instant Pot liner/pot.
Add bay leaf, garlic, dashi kombu, shiitake mushrooms, etc. to the basket.
Insert the basket into your Instant Pot liner.
Pour enough filtered water to cover the scraps – do NOT exceed MAX fill line.
Place the liner into your Instant Pot.
Select the soup/broth setting (or high pressure) on your Instant Pot.
Increase/decrease the time to 30-40 minutes. (I normally use 40 minutes.)
Once the cycle is complete, allow the Instant Pot to naturally release pressure.
Strain your broth by removing the basket insert or using a mesh colander.
With a ladle and funnel, carefully transfer the broth into sterilized mason jars.
Place clean lids on each jar to seal them up. Each jar should seal within 1-2 hours.
Once cool, place the jars in the refrigerator for up to 2 weeks.
Notes
You can use just about any vegetable scraps, including onions, carrots, and celery, tomatoes, bell peppers, herbs (especially bay leaves and parsley), spinach, corn, green beans, etc. You can also use smaller portions of brassicas like cabbage, broccoli, cauliflower, brussel sprouts, turnips, turnip greens collard greens, kale, and bok choy.I like to use the soup/broth setting on my Instant Pot; but you can use the high pressure setting on any pressure cooker. The idea is to extract the flavor and umami from the contents. Once the 'extraction' process is complete, strain, and pour the broth into sterilized mason jars, seal them up with lids. Once cool, place the jars in the refrigerator for later use. The heat should seal the lids so they should be good for a couple weeks in the refrigerator.If you don't have a pressure cooker, you can use a slow cooker (or on the stove) for 4 hours on high or 6-8 hours on low. Strain and bottle per the above instructions.