Add beans, onion and vegetable broth to the Instant Pot. Pressure cook on high for 30 minutes, then naturally release for 20mins.
Carefully remove lid once steam has fully escaped. The beans should be tender and perfectly cooked, but if they're not that's usually caused by having old beans or hard water – you can seal the lid again and pressure cook on high for an additional 10-20 minutes, or until they're tender.
Remove onion and strain off any excess cooking liquid (or sauté for 10 minutes with the lid off, stirring frequently, to evaporate excess liquid).
Enjoy immediately, or store cooled leftovers in the refrigerator up to 5 days or in the freezer up to 1 month.
