- 1 (1-pound) piece beef tenderloin
- 2 tablespoons soy sauce
- 2 tablespoons sugar
- 1 tablespoon medium-dry Sherry
- 1 1/2 teaspoons Asian sesame oil
- 2 teaspoons cornstarch
- 1 1/2 pound baby bok choy
- 2 tablespoons soy sauce
- 3 tablespoons medium-dry Sherry
- 1 teaspoon balsamic vinegar
- 1 cup vegetable oil
- 1 1/2 tablespoons minced garlic
- 1 tablespoon minced peeled fresh ginger
- Accompaniment: rice
- Cut beef crosswise (across the grain) into 1/4-inch-thick slices, then cut slices into 1/2-inch-wide strips.
- Stir together marinade ingredients in a medium bowl until sugar is dissolved.
- Add beef, tossing to coat, and marinate 30 minutes to 1 hour.
- Separate bok choy into individual leaves and halve crosswise, keeping stems and leaves separate. Cook stems in a large pot of boiling water 15 seconds, then add leaves and cook 15 seconds more. Drain in a colander, then rinse with cold water to stop cooking and drain well.
- Stir together soy sauce, Sherry, and vinegar.
- Heat vegetable oil in a 12-inch heavy skillet over moderate heat until a deep-fat thermometer registers 400°F.
- Add beef to hot oil with tongs (discard marinade) and cook, stirring carefully, until slices separate, about 1 minute. Transfer beef with tongs to a colander and drain.
- Reserve 3 tablespoons oil from skillet and discard remainder. Heat reserved oil in skillet over moderately high heat until hot but not smoking, then stir-fry garlic and ginger until fragrant, about 30 seconds. Add beef, soy mixture, and bok choy and stir-fry until sauce is simmering and mixture is just heated through, about 1 minute. Serve immediately.