It's easy to create your own Chinese stir-fry dishes at home if you have a good skillet or wok. Beef and broccoli are a classic combination, but for asparagus makes a nice change of pace. The beef is marinated for a short period to tenderize the meat and enhance its flavor. Stir-frying is a quick way to cook, so assemble all the various components of the dish before you start cooking for the best results.
Place the beef and half of the soy sauce in a small bowl and stir to combine. Cover the bowl and refrigerate for 30 minutes, stirring once. Drain the beef well and discard the liquid.
Combine 1 teaspoon of the peanut oil with the garlic and ginger in a small bowl and set aside.
In another small bowl, whisk together the remaining soy sauce, sherry, water, oyster sauce, sugar, sesame oil, and cornstarch and set aside.
Snap off the tough ends of the asparagus and discard. Unless you're using pencil-thin asparagus, peel the stalks. Cut the asparagus on a diagonal into 2-inch pieces. Set aside.
Heat a large (12-inch) skillet or wok over high heat until very hot. Add one tablespoon of peanut oil and the drained beef. Cook without stirring for 1 minute, and then stir the beef and continue cooking until the edges of the meat brown, about 30 seconds. (It's important to sear the meat in a very hot pan over high heat in order to brown it quickly.) Transfer the beef to a platter.
Add the remaining 2 teaspoons of peanut oil to the pan (no need to clean it) and place over high heat. When the oil is hot, add the asparagus and cook for 30 seconds. Add 2 tablespoons of water to the pan, cover, and lower the heat to medium. Cook until the asparagus is crisp-tender, 1 to 2 minutes. Transfer the asparagus to a plate and set aside, uncovered.
Return the skillet to high heat and add the oil, garlic, and ginger mixture, stirring constantly until fragrant, about 15 seconds. Add the beef, asparagus, and water chestnuts, if using, to the pan, and stir to combine. Quickly whisk the sherry-cornstarch mixture to recombine, and add the sauce to the skillet. Cook, stirring constantly, until the sauce thickens to coat the meat and asparagus, about 1 minute.
Transfer to a serving platter and sprinkle with the sesame seeds. Serve immediately.