In a large, heavy-bottomed pot or skillet, sauté the onion in olive oil for about 3-5 minutes. Add the bell pepper and cook for another 3-4 minutes.
Add the garlic, cumin, and red pepper flakes. Cook for a minute.
Add the diced tomatoes and keep cooking, stirring occasionally for 5 minutes.
At this point, add the rice and veggie broth. Stir everything well and bring to a boil. Cover with a tight lid, reduce the heat to low, and simmer for about 45 minutes,* or until the rice is cooked through.
Stir in the black beans and cilantro. Let it rest for 5 minutes. Serve.