In the meantime, heat the oil in a saucepan over medium heat. Sauté the garlic, onion, and cumin until the onions start to soften. Add in the black beans and season with salt and pepper. Fill the can about 1/4 to 1/3 of the way with water (depending on how many portions you are making) and swish it around to incorporate anything leftover in the can then add to the saucepan.
Simmer for 15-20 minutes to concentrate the flavor. Add more cumin if needed and season with salt to taste. Remove from the heat and stir in the cilantro. Season with salt and pepper to taste.