Prepare the Beef : In a bowl, combine the beef strips with soy sauce, white pepper, baking soda, sesame oil, sugar, and Chinese five spice.
Coat the Beef : Beat the egg whites in a shallow dish and mix with cornstarch until a thick batter forms. Dip each piece of marinated beef into the batter, ensuring a thorough coating.
Fry the Beef : Heat vegetable oil in a deep pan or wok to 350°F (180°C). Fry the beef in batches until golden and crispy, about 2–3 minutes per batch.
Prepare the Vegetables : In a clean wok or large skillet, heat peanut oil over medium-high heat. Add minced garlic and stir-fry until fragrant. Toss in onion, bell pepper, and red chili pepper.
Make the Sauce : In a bowl, whisk together rice vinegar, brown sugar, ketchup, tomato paste, Hoisin sauce, cornstarch, and soy sauce. Pour the sauce into the wok with the vegetables.
Combine and Serve : Add the fried beef to the wok and toss until evenly coated with the sauce. Serve immediately with steamed rice or noodles.