Prepare dressing: in a small mixing bowl whisk together olive oil, lime juice, lime zest, cilantro, cumin and garlic. Add remaining ingredients to a bowl: to a large bowl add brown rice, black beans, tomatoes, bell pepper, jalapeno, corn, red onion and avocado. Toss with dressing: pour lime mixture over ingredients rice mixture and toss to evenly coat while seasoning with salt and pepper to taste.