In a medium bowl, sprinkle the beef with salt and pepper. Add the cornstarch and mix well. Set aside.
In another smaller bowl, stir together the ketchup, rice wine, soy sauce, vinegar and chili sauce. Set aside.
In a small pan over medium heat, toast the Sichuan peppercorns until fragrant, 1 to 2 minutes. Remove from the heat and crush 1/2 tablespoon of the peppercorns in a mortar and pestle, or in a plastic bag with a rolling pin. Set aside. Leave the remaining peppercorns whole.
Heat a wok over high heat and, when wok starts to smoke, add the peanut oil. Add the remaining whole Sichuan peppercorns, dried chiles and fresh chiles and stir-fry for a few seconds. Add the beef and stir-fry until the beef is brown, 2 to 3 minutes. Add the reserved sauce and peanuts and cook until the sauce has reduced slightly and is sticky and has a thicker consistency. Add the cilantro and scallions and toss to coat and warm through. Then transfer to a serving plate and garnish with the ground Sichuan peppercorns. Serve immediately.