Start by cooking the Knorr Mexican or Spanish rice according to package instructions. Fluff it well once done.
In a small mixing bowl, combine 1 cup sour cream, 1/2 cup buttermilk, 1 ripe avocado, 1 teaspoon chopped garlic, 1 teaspoon lime juice, and 2 teaspoons dry ranch dressing mix. Blend thoroughly until smooth and creamy.
Pat the chicken breast dry and season with 1/2 teaspoon salt and 1/4 teaspoon ground black pepper. Heat 2 teaspoons olive oil in a skillet over medium heat, then add the chicken. Cook for 5-6 minutes per side or until internal temperature reaches 165°F (74°C). Slice into bite-sized strips.
In a bowl, mash 2 small or 1 large avocado with 1 tablespoon diced red onion, 1 teaspoon diced tomato (reserved), 2 teaspoons lime juice, and a pinch of salt. Mix until well combined but still chunky.
Assemble the bowl starting with the cooked Mexican rice, then add sliced chicken, black beans, shredded lettuce, and chopped tomato. Spoon dollops of guacamole and creamy avocado lime sauce over the top. Sprinkle shredded Cheddar cheese and add low-fat sour cream.
Serve immediately while the chicken is warm and flavors are fresh. Enjoy!