Preheat oven to 425°F. Dust a baking sheet with cornmeal. On a lightly floured surface, stretch or roll the pizza dough into a 14- to 16-inch oval. Transfer to the prepared baking sheet.
In a large skillet over medium heat, cook the ground beef until no longer pink, breaking it up with a spoon, about 5 minutes. Remove from heat and stir in the barbecue sauce.
Spoon the beef mixture over the prepared dough and sprinkle evenly with grated Cheddar.
Bake until the crust is golden brown and crisp, 20 to 25 minutes.
While pizza bakes, toss together the lettuce, cherry tomatoes, and red onion with olive oil, 1/4 teaspoon salt, and 1/4 teaspoon pepper in a large bowl.
Top the baked pizza with the salad mixture. Slice and serve immediately.