Trim the fat from the beefsteak and cut the beef with the grain into 2-inch-wide pieces. Slice across the grain into 14-inch-thick slices. Stack the slices and cut into thin strips. Toss the beef with 2 teaspoons vegetable oil, salt, white pepper and cornstarch in a medium-size bowl. Cover and refrigerate for 30 minutes.
Core, seed and cut the red pepper into thin strips. Cut the jalapeño chile in half lengthwise; remove the seeds and membrane; cut into very thin strips.
Heat a heavy nonstick skillet or wok over high heat. Add the remaining tablespoon oil and heat. Add beef, ginger and garlic and stir-fry for 1 minute. Add the red pepper and the jalapeño and stir-fry for 1 minute. Add hoisin sauce and stir over high heat for 30 seconds. Add peanuts; mix well. Makes 2 servings.