Curious, we decided to experiment by varying Guerra's recipe. Here's what we found out: soaking dried beans overnight is fine, and even good, in that it reduces the cooking time by at least a quarter, but if you have the time for a longer simmer, then soaking isn't necessary. As for the quick-soaking method—i.e., bringing the beans to a boil and then letting them sit for an hour—we found that an hour in warm water made virtually no difference in the cooking time, so go for either the overnight soak or none at all. And the salt? Adding it didn't change the texture of the beans or alter the cooking time, so salt as freely as your taste dictates. A final revelation: for one version we tried, we removed the tomatoes and noticed that the beans cooked a lot faster. Acidic ingredients, it turns out, slow down the cooking process dramatically. Who knew?