To make rice: substitute 1 can of undrained diced tomatoes for 2 cups water. Add additional water to make up the difference needed. Stir in chili powder and cumin. Cook rice according to package directions.
Meanwhile: Heat olive oil in large skillet to medium-high heat. Add onions and bell peppers. Cook 3–4 minutes, until fragrant. Add in ground beef, salt and pepper. Cook 5–7 minutes, stirring occasionally and breaking up meat, until meat is browned and cooked through (drain any excess fat). Add cooked rice, drained pinto beans and remaining can of drained diced tomatoes. Stir and cook 3–4 minutes more until heated through.
Spoon over bed of chopped lettuce and garnish with cilantro. Sprinkle with diced avocado, shredded cheese and/or sour cream.