Heat oil in a large saucepan over medium heat. Sauté onion, bell pepper, and garlic. When onion is translucent, add salt and tomato paste. Reduce heat to low and cook, 2 minutes. Stir in beans and rice.

Pour liquid from beans into a large measuring cup and add enough water to reach a volume of 2 1/2 cups; pour into beans. Cover and cook on low, 45 to 50 minutes, or until liquid is absorbed and rice is cooked.