In a large bowl combine rice, lettuce, tomatoes, beans, avocado, onions, cilantro, and cheese and toss lightly.
In a small bowl, whisk together olive oil, lime juice, vinegar, salt, chili powder, and cumin.
Pour dressing over salad and toss to coat evenly. Divide between 6 bowls or plates and garnish each with a tablespoon of sour cream to serve
TIP: Add a sprinkle of taco chips to top off this fiesta with a crunch.