Preheat oven to 375 degrees F. Coat a deep-dish pie pan or other 9-inch round baking dish with cooking spray.
Heat leftover pork and sauce just until warm. Combine with tomatoes and chorizo (or pepperoni) in a bowl. Mix well. Spread about 1/2 cup of the mixture in the prepared pan to cover the bottom. Top with 1 tortilla. Spoon one-third of remaining mixture over the tortilla. Repeat twice, topping with the fourth tortilla. Drizzle the reserved tomato juice over the top and cover with foil.
Bake for 20 minutes. Remove the foil, sprinkle cheese on top and continue baking until the cheese is melted and the torta is bubbly, about 20 minutes more. Let cool for 10 minutes. Serve sprinkled with scallions and cilantro, if desired.
Pulled Pork with Caramelized Onions
1 1/2 starch, 2 vegetable, 2 1/2 lean meat