SORT the split peas and remove any stones or debris.
SOAK the split peas in enough water to cover them by at least three inches. Soak them at least 8 hours or overnight.
DRAIN and RINSE the split peas.
PEEL and CHOP the onion, carrots, potato, and celery.
POUR the broth into the pressure cooker container. Add the drained split peas, onion, carrots, celery, and potato.
SPRINKLE in the salt, pepper, thyme, oregano, and parsley. Stir to combine.
ADD the ham bone. Make a well in the center of the soup and place the ham bone in the well. Top the soup with 2 bay leaves.
SECURE the lid to the pressure cooker.
PRESSURE COOK on high pressure for 15 minutes, or until the split peas and vegetables are soft. Manually release the pressure if you are in a hurry. Or allow the pressure to release naturally. Either method is fine.
REMOVE the bay leaves and ham bone when the soup has finished cooking.
PULL OFF any ham that is falling off the bone and add the small pieces back into the soup. Use the ham bone for another recipe or discard it.
STIR the soup to combine.
GARNISH with ham, crumbed bacon, or crunchy croutons.