Preheat the grill for high heat and lightly oil the grate.

Cook chicken on the preheated grill until the juices run clear, about 6 minutes per side. An instant-read thermometer inserted into the center should read at least 165 degrees F (74 degrees C). Remove from heat, cool, and slice.

In a large bowl, mix lettuces, tomato, cilantro, corn, and black beans. Top with grilled chicken slices and French fried onions.

In a small bowl, mix ranch dressing and barbecue sauce together. Serve on the side as a dipping sauce or toss with the salad to coat.