Place pinto beans in your instant pot with water, onion, salt, and cilantro if you're using it.
Pressure cook beans on high pressure for 45 minutes.
When the beans are done cooking let the pressure release naturally from the instant pot.
Note: If you do not have an instant pot or pressure cooker, cook beans according to package instructions.
When the beans have finished cooking, place them in a high speed blender with ½ cup of the water remaining in the pressure cooker.
Blend on high speed until smooth.
Add salt to taste.