1. Cut the beef across the grain into thin slices, ideally 1½ by 1¼ inches. Add the marinade ingredients and mix well.

2. Heat the peanut oil to about 275°F. Add the beef and stir gently. As soon as the pieces have separated, remove them from the oil and drain well; set aside.

3. Pour off all but 3 tablespoons of the oil. Over a high flame, add the ginger, garlic, fresh chiles, chili flakes, and cumin and stir-fry briefly until fragrant. Return the beef to the wok and stir well, seasoning with salt to taste.

4. When all the ingredients are sizzlingly fragrant and delicious, add the scallion greens and toss briefly. Remove from the heat, stir in the sesame oil and serve.