5 How to cook white kidney beans Wash white kidney beans and soak them in cold or warm water 12 hours. When the beans are completely swollen, pour out the water, add water and cook in a pressure cooker for 20 minutes, or simmer with slow fire, and store the cooked beans in the refrigerator. In urgent need, the washed dried beans can be boiled in water for 2 minutes, and then simmered for 2 hours with low fire, which can make the beans completely expand, so it is easy to cook.