In a pressure cooker, heat olive oil. Saute the onion till wilted.
Add the celery and carrot and cook for a couple of minutes.
Add in the parsley, oregano, beans and water and give it a good mix. Adjust seasoning.
Cook on high for 3 whistles. Switch off and allow the pressure to go by itself.
Open the lid, check if the beans are done. Adjust seasoning, add more water if required - I added a cup more and simmer.
Serve warm for a filling meal!