Place a large sauce 6-8 quart pot over medium heat. Add the oil, chopped bell peppers, onions, and garlic. Saute for 3-5 minutes to soften.
Add whole chicken breasts, black beans, diced tomatoes, chicken broth, 1 fajita seasoning packet, and 1/2 teaspoon salt. If adding rice, stir it in with an additional 2 cups of water. Bring the soup to a boil. Lower the heat, and simmer for 20 minutes.
Use tongs to remove the cooked chicken breasts. Allow the soup to continue simmering to fully cook the rice, another 10-15 minutes. Allow the chicken to cool for a few minutes, then shred with two forks.
Once the rice is tender, add the shredded chicken back to the soup. Taste, and salt and pepper as needed.
This soup has a nice light fajita flavor. If you like a more robust soup, use the fajita packet + 1 teaspoon ancho chili powder, 1 teaspoon cumin, and 1 fresh chopped jalapeno.For a low carb option, omit the brown rice.