Peel the 2 large onions, quarter and place in the Instant Pot.
Scrub the carrots, trim the ends, cut into 3-4 pieces and add to the Pot.
Wash the celery stalks, trim the ends, cut into large pieces add to the onions and carrots.
Wash the herbs well and remove any discolored leaves. Add herbs to the Pot and cover the mixture with 12 cups of water.
Cover the Instant Pot with the lid, close the vent and set the machine to Manual High Pressure, 30 minutes.
When the timer signals 30 minutes, turn off the pot and open the vent to release pressure.
Place the strainer over a large pot or container. Pour the hot broth carefully into the strainer.
Add salt and pepper to the broth. Adjust seasonings per taste preference.
Use immediately for a recipe, or store for later use (canning jars or plastic containers for freezing).