Recipe adapted from many plates of beans and rice I tasted in Costa Rica, and from this recipe on Boulder Locavore, which is most like the gallo pinto I enjoyed at least once a day. Serves 4-6 as a side dish.
2 cups cooked black beans, plus 3/4 cup bean cooking liquid (can be made days in advance)
3 cups cooked long-grain white rice, cooled (can be made days in advance)
1 Tbsp vegetable oil
1/2 onion, diced
1 bell pepper, diced (in Costa Rica, this would be a green pepper, but I love the red)
1/2 cup diced celery
2 large cloves garlic, minced
1 tsp dried thyme leaf
1/2 tsp kosher salt, or more to taste
1/2 tsp fresh black pepper, or more to taste
Chopped cilantro for garnish (optional)
I used a pressure cooker to cook a batch of dry black beans, with no presoaking, in less than an hour (wow!). You can cook beans in a slow cooker or stovetop pot. Any way you prepare them, beans made from scratch will have a more firm texture than canned beans. Make the beans way ahead, even days ahead, and store them in the refrigerator. In a pinch, of course you can use canned black beans; reserve some of the bean liquid before rinsing the beans.
In a large, deep frying pan, heat the oil over medium heat. Sauté the onion for 2 minutes, until translucent. Add the bell pepper and celery, and continue to cook for 3 minutes. Toss in the garlic and thyme, and stir for 30 seconds.
Gently pour the black beans and reserved 3/4 cup of bean cooking liquid into the pan. Stir well to combine, and try not to break up the beans. Bring the mixture to a simmer. Then, add in the rice, breaking up clumps with your fingers as best you can.
Stir the rice and bean mixture together so that all of the liquid coats the grains of rice, turning them a brownish color. Season with salt and pepper (this dish needs a lot of salt to be authentically Costa Rican, so don't be afraid to add more than the recipe calls for).
Top with chopped fresh cilantro for serving, if you wish.