To coat the beef, in a bowl, add the beef and toss with the cornstarch until evenly coated.
To fry the beef, in a wok or deep pan over high heat, add the cooking oil and heat to 350°F (177°C). Add the beef in batches, separating the pieces gently, and fry for about 3 minutes until golden and crispy, then remove and drain.
To make the sauce, in a bowl, mix the soy sauce, rice vinegar, rice wine, sugar, sesame oil, and red pepper flakes until combined.
To stir-fry and combine, in a clean wok over high heat, add the cooking oil, then add the carrots, scallions (white parts), ginger, and garlic, and stir-fry for about 30 seconds until fragrant. Pour in the sauce and bring to a boil, then stir the cornstarch with the water to form a slurry and add it to the wok, stirring until the sauce thickens slightly. Return the crispy beef to the wok and toss quickly to coat, then add the scallions (green parts) and give it one final toss before serving immediately.