Cuban Black Beans

Bring 1 lb. dried black beans, picked through, rinsed, 1 bay leaf, ¼ cup finely chopped medium onion, ¼ cup finely chopped green bell pepper, seeds and ribs removed, 1 Tbsp. grated garlic cloves, 5 tsp. Diamond Crystal or 1 Tbsp. Morton salt, ½ tsp. dried Mexican or Italian oregano, and 5 quarts water to a boil in a large pot. Reduce heat to medium and cook, stirring occasionally and adding more hot water if needed to cover, until beans are tender and covered by about ¼" liquid, 2½–3 hours. Discard bay leaf.

Meanwhile, heat ¼ cup extra-virgin olive oil in a medium skillet over medium. Add remaining onion, bell pepper, garlic, and ½ tsp. dried Mexican or Italian oregano; season with kosher salt and freshly ground black pepper. Cook, stirring occasionally, until onion mixture is very soft and beginning to brown, 15–20 minutes. Stir into cooked beans. Top with cilantro leaves with tender stems, if using. Do Ahead: Beans can be made 3 months ahead. Transfer to an airtight container and freeze.