To make the rice, bring water to a boil, add rice (1 cup) and kosher salt (1/2 teaspoon), stir, and simmer until cooked (about 15-20 minutes). When done, fluff with a fork, stir in the cilantro and lime juice, and adjust seasonings if necessary.
While the rice is cooking, make the beans. Sauté the diced onion in the olive oil (1 tablespoon) over medium-high heat in a medium pot until softened and beginning to brown (about 2-3 minutes).
Add drained and rinsed black beans, cumin (1 teaspoon), kosher salt (1/2 teaspoon), and water (1 cup). Stir, bring to a boil, and simmer uncovered for about 10 minutes.
Turn off the heat. Use a potato masher to mash the beans a few times, thickening the mixture, but leaving most of the beans intact. If you don't have a potato masher, you can use a fork on the side of the pot.
Stir in the lime juice and fresh chopped cilantro (2 tablespoons) and season with more salt if necessary.
Serve the beans on top of the rice as a side or meal.
Feel free to use brown rice instead of white if you prefer; be prepared to double the cooking time and pay attention to the ratio of water to rice you should use based on the instructions on the package. Basmati or other kinds of rice can also be used.
If you don't have the fresh onion, cilantro, and/or lime juice on hand, dry pantry ingredients can be substituted. Use ground coriander and onion powder in the beans.
For a grain-free version, substitute your favorite cauliflower rice recipe to serve the beans with.
The provided nutrition information does not include any added sodium from seasoning to taste, any optional ingredients, and it does not take brands into account. Feel free to calculate it yourself using this calculator or by adding the recipe to Yummly.