Charred Veggie Flatbreads

In large bowl, toss first 5 ingredients. Grill over high heat, turning often, until charred in spots, about 3 minutes for avocado and 5 to 8 minutes for remaining vegetables. Slice bell pepper into strips and chile into rings. Separate onion into rings. Grill naan until slightly charred, about 2 minutes. Spread naan with mayonnaise. Peel and slice avocado. Top naan with avocado, grilled vegetables, tomato, and cilantro; season.