In a medium ziplock bag, place the chicken breasts, taco seasoning, cumin, salt, lime juice and olive oil. Shake until fully combine and chicken is coated. Allow to marinate for 10 minutes or up to 2 days in advance.
To cook chicken: heat a heavy skillet to medium/high heat (Be sure the skillet is very hot before adding chicken). Add 1 teaspoon oil of choice to skillet. Place the chicken on a skillet and cook for 4-5 minutes on each side. Allow chicken to rest in pan for at least 5 minutes before cutting.
To make the dressing: Place the sour cream (or greek yogurt), cilantro, lime juice, and salt in a blender or food processor. Pulse for a few seconds or just until the cilantro is fully chopped.</li>
To Assemble: Place the chopped romaine lettuce on the bottom of a salad plate. Top with avocado, chopped tomatoes, black beans, corn, cilantro, and sliced chicken. Top with cold creamy cilantro dressing just before serving. Enjoy!