1. Mix the soy sauce, vinegar, and five spice powder together in a bowl. Add the beef and toss well. Season well with black pepper. Cover and refrigerate for at least 2 and up to 12 hours.

2. Heat 2 tbsp oil in a wok over high heat. Add the bell pepper and stir-fry until crisp-tender, about 3 minutes. Add the chile, garlic, and ginger and stir-fry for 1 minute. Add the broccoli and snow peas and stir-fry for 2 minutes. Transfer to a platter.

3. Add the remaining oil to the wok and heat over high heat. Drain the beef from the marinade, reserving the marinade. Add the beef to the wok and stir-fry for 1 minute. Return the vegetables to the wok and pour in the marinade. Dissolve the cornstarch in the stock, and stir into the wok. Stir-fry the steak and vegetables until the sauce is boiling.

4. Transfer to a plate, drizzle with the sesame oil, and serve at once.

Variation:

Chicken Chile Stir-fry: Substitute skinless and boneless chicken breast for the beef.