Trim the fat from the beefsteak and cut the beef with the grain into 2-inch pieces. Slice across the grain into ¼-inch slices. Stack the slices and cut into thin strips. In a medium bowl, toss the beef with 2 teaspoons vegetable oil, the salt, white pepper, and cornstarch. Cover and refrigerate for 30 minutes.

Core, seed, and cut the red bell pepper into thin strips. Cut the jalapeno pepper in half lengthwise, remove the seeds and membrane, and cut into very thin strips.

Heat a nonstick skillet over high heat. Add the remaining 2 tablespoons vegetable oil, the beef, ginger, and garlic and stir-fry for 1 minute. Add the red bell pepper and the jalapeno pepper and stir-fry for 1 minute. Add the hoisin sauce and stir over high heat for 30 seconds. Add the peanuts and mix well.