Whisk taco sauce, mustard, and lime juice together in a shallow baking dish; add the chicken and turn to coat. Cover the bowl with plastic wrap and marinate in the refrigerator 1 to 4 hours.Advertisement
Remove chicken from marinade and shake to remove excess moisture; reserve marinade.
Melt butter in a large skillet over medium heat. Cook chicken in melted butter until no longer pink in the center and the juices run clear, 5 to 7 minutes per side. An instant-read thermometer inserted into the center should read at least 165 degrees F (74 degrees C). Pour reserved marinade into the skillet; continue cooking until the marinated is hot and reduces in volume slightly, 3 to 5 minutes. Top each breast with a dollop of sour cream.
Reynolds® Aluminum foil can be used to keep food moist, cook it evenly, and make clean-up easier.