Preheat the oven to 500ºF.
Roll out the pizza dough on a lightly floured surface until it is roughly 12 inches wide and 1/4-inch thick.
Invert a baking sheet and sprinkle it liberally with cornmeal. Transfer the dough to the baking sheet.
In a medium bowl, toss together the diced chicken with half (1/4 cup) of the barbecue sauce. Spread the remaining 1/4 cup barbecue sauce on the dough, leaving a 1/2-inch border around the edges. (See Kelly’s Notes. Depending on the shape of your pizza, you may want to add more sauce.)
Sprinkle the mozzarella cheese atop the barbecue sauce, and then evenly distribute the coated chicken atop the cheese. Scatter the red onions atop the chicken.
Bake the pizza for 10 to 12 minutes, rotating it half-way through, until the crust is fully baked and golden brown. Remove the pizza from the oven to a cutting board, sprinkle it with chopped cilantro, slice and serve.