Cook the brown rice according to package instructions and let it cool.
In a large mixing bowl, combine the black beans, avocado, red bell pepper, red onion, cherry tomatoes, and cilantro.
In a separate small bowl, whisk together lime juice, olive oil, salt, and pepper.
Pour the dressing over the salad ingredients and gently toss to combine.
Fold in the cooled brown rice carefully, mixing until evenly distributed.
Taste and adjust seasoning if necessary, adding more lime juice, salt, or pepper as desired.
Serve immediately or chill in the refrigerator for 30 minutes before serving.