My method for pressure cooking beans:
1. I read in a test kitchen cook book that for the best results for cooked beans they should be brined in salt water and soaked for a long time. I soak two cups of dried beans in a bowl of water with at least 1 tablespoon of salt. The book recommends two tablespoons of salt because the chemical compound of salt reacts with the calcium in the bean shell to soften it. Then I let them soak for 24 (yup 24) hours.
2. I rinse the beans, but I suppose if water were scarce I could just drain them and put them in the pressure cooker. Cover with water about an inch higher than the beans. I season them at this time. I like the way the canned bean brand Sun Vista pinto beans taste and they add salt and sugar plus some other things I can't remember right now.
3. I bring the beans up to pressure and cook for 10 to 12 minutes. By twelve minutes I usually have a nice gravy. I let the pressure release naturally. If the beans are not soft enough at this point, I just bring them back up to pressure and cook for another 5 minutes.
This method also works for the smallish garbanzo beans I get at the 99-cent store.
Tracy