01 - Combine sliced beef with 1 tbsp soy sauce, cornstarch, and sesame oil in a medium bowl. Mix thoroughly and let marinate for 10 minutes at room temperature.
02 - Whisk together all sauce ingredients in a small bowl until sugar dissolves completely. Set aside for later use.
03 - Heat 1 tbsp oil in a large wok over medium-high heat. Add green beans and stir-fry for 4–5 minutes until blistered and just tender. Remove from wok and set aside.
04 - Add remaining oil to the wok. Add Szechuan peppercorns and fry for 30 seconds until fragrant, being careful not to burn them.
05 - Add marinated beef to the wok and stir-fry for 2–3 minutes until browned and just cooked through. Push beef to the side of the pan.
06 - Add garlic, ginger, scallions, and chili to the center of the wok. Stir-fry for 1 minute until fragrant, then combine with the beef.
07 - Return green beans to the pan. Pour in the prepared sauce and stir everything together. Cook for 2–3 minutes until heated through and sauce thickens slightly.
08 - Transfer to a serving platter and serve hot with steamed jasmine or brown rice.