Combine the drained beans, water, onion, and garlic in the Instant Pot.
Stir well, making sure the beans are submerged. Secure the lid and move the steam release valve to Sealing. Select
Manual/Pressure Cook to cook at high pressure for 20 minutes.
When the cooking cycle is complete, let the pressure naturally release for 10 minutes, then move the steam release valve to Venting to release any remaining pressure. When the floating valve drops, remove the lid and drain the beans, reserving the liquid.
Return the cooked beans to the Instant Pot, and stir in ½ cup of the reserved cooking liquid, along with the cumin, chili powder, black pepper, cayenne, and ½ teaspoon salt. Use a potato masher to mash the cooked beans until smooth, leaving some texture if you like. (You can use an immersion blender for pureed beans, if you prefer.)
Taste and adjust the seasoning, adding more salt as needed, and serve warm with a garnish of cilantro and a squeeze of lime juice.
Store leftover beans in an airtight container in the fridge for 1 week.