Our weeknight adaptation of Diana Kennedy’s lightly spiced Oaxacan white bean guisado (stew) from “Oaxaca al Gusto” uses canned small white beans instead of starting with dried beans. This means the dish is ready to serve in well under an hour. We spoon a simple salsa of fresh tomatoes, chopped onion and parsley—thrown together while the beans simmer—onto individual servings to add bright color and flavor.