Rinse the beans in a colander under cold water. Soak the beans.
Place the beans in the pressure cooker. Add the onion, garlic, green bell pepper, bay leaf, and water.
Cover and bring to HIGH pressure over high heat. Lower the heat to stabilize the pressure. Cook for 12 minutes (or 18 minutes on LOW pressure).
Release the pressure automatically.
Unlock and open the lid. Taste the beans. If they’re still hard, return to step 3 and cook for an additional 2 to 4 minutes or until tender.
Remove and discard the onion, garlic, green bell pepper, and bay leaf. Season with salt.
If not using the cooked beans right away, store them in their cooking liquid, in a covered container in the refrigerator, up to a week.