Sort through your pinto beans and pull out all the broken pieces and rocks.
Rinse them good, then place in a large bowl and fill with water. 3-4 inches over the top of the beans.
Let the beans sit overnight, or for at least 6-12 hours. *NOTE: if you're in a hurry, you can do a quick soak. Put beans in a pot with water, heat on the stove until just starting to boil. Shut off the heat and let the beans soak for 2-4 hours.
Rinse beans again before adding to the pressure cooker. Add 9 cups of fresh water. Cover the pressure cooker with the lid. Make sure your valve is on "sealing." The valve is on top of the lid.
Push the Manual button and set to 50 minutes, then just walk away.
Once the pressure cooker beeps and is done, let is rest for 10 minutes (or more).
Quick release (by turning the valve to venting). Allow all the pressure to escape and the red button goes down. If you have time, you can let the pressure come down naturally.
Open the lid and season your beans with salt (about 3 teaspoons). You're done! Store in the fridge for 5-6 days, or in the freezer for 3 months.