Better than anything you can get at your local takeout joint, this way of making the Chinese classic can be done in record time.
Heat 1 tablespoon oil in a 12-inch heavy skillet over high heat until hot but not smoking, then cook eggs, stirring, until just cooked through. Transfer scrambled eggs to a plate. Add remaining 3 tablespoons oil to skillet and heat until hot but not smoking, then cook ginger, garlic, and red pepper flakes, stirring, until garlic is golden, about 1 minute. Add coleslaw mix and 2 tablespoons water and cook, covered, stirring occasionally, until coleslaw is wilted, about 5 minutes.
Stir together soy sauce, sesame oil, remaining 2 tablespoons water, and hoisin sauce in a small bowl. Add to coleslaw mixture along with scallions and eggs and cook, stirring, 2 minutes. Remove from heat. Immediately put tortillas between 2 dampened paper towels on a microwave-safe plate and microwave on high power until tortillas are hot, about 1 minute.
To assemble, spread hoisin on each tortilla and top with mu shu mixture, shredded chicken and scallions, then roll up.