Grill chicken over medium-high heat until internal temperature reaches 165 degrees Fahrenheit, brushing with 1/4 cup BBQ sauce in the final minutes.
Allow chicken to rest for 5 minutes before dicing into 1/2-inch cubes.
Combine lettuce, black beans, corn, tomatoes, and red onion in a large vessel.
Whisk together ranch dressing and remaining BBQ sauce to create the dressing base.
Incorporate chicken, cheese, cilantro, and avocado into the vegetable mixture.
Apply dressing and toss until components are evenly coated.
Top with tortilla strips and serve immediately.