Perhaps your new favorite bean dish:
Soak the beans for one night. The following day, pour off the water and rinse the beans with fresh water. Fill with cold water, add the chopped onion and do everything together with the lid closed at a low temperature. After about 3 hours the bean skin will start to crack. This is the time to add the lard or oil. Only when the beans are cooked completely soft, season with a tiny bit of salt.
Source : Mexican recipe collection Thomas Behrens ( 2:2426/3075.20 ) **