Cut pork into 1/4-inch-thick slices.
Combine cornstarch, next 3 ingredients, and, if desired, red pepper in a large zip-top plastic bag. Add pork in batches; seal and toss to coat.
Brown one-third of pork in one-third of oil in a large nonstick skillet over medium heat, stirring occasionally. Drain on paper towels, and repeat procedure twice. Combine cooked pork and chiles in skillet, and cook until thoroughly heated.
Heat tortillas according to package directions. Spoon pork mixture evenly down the center of each tortilla; top with desired toppings, and roll up, jellyroll fashion. Serve with Pico de Gallo.