The seasoning in this recipe is very basic so you can make a big batch of pinto beans for the week and add specific spices later. Try adding thyme, parsley, sage and a Parmesan rind for Italian cooking or fresh cilantro and peppers for more Mexican flavors.
Place beans and soaking water in a large, heavy pot. Add halved onion and bring to a gentle boil. Skim off any foam that rises, then add garlic and bay leaf, reduce heat, cover and simmer 30 minutes.
Add salt and continue to simmer another 1 to 1 1/2 hours, until beans are quite soft and broth is thick and fragrant. Taste and adjust salt. Using tongs or a slotted spoon, remove and discard onion and bay leaf. For the best flavor refrigerate overnight.
Cooked beans will keep for 3-4 days in the fridge and can also be frozen in small batches for later use.