1.If using beef sirloin, slice into thin strips and set aside. Wash bok choy, separating leaves slightly to remove grit. If using regular bok choy, cut out and discard thick core. Slice leaves and stalks crosswise into 1-inch (2.5-cm) strips. They should measure about 8 cups (2 L) loosely packed. If using baby bok choy, keep leaves whole if they are very small. Or slice leaves crosswise into 1-inch (2.5-cm) strips and slice stalks into halves or quarters.
2.Thinly slice green onions diagonally. If using fresh garlic, finely mince. In a small bowl, stir teriyaki with cornstarch until dissolved. Then stir in garlic, wine, honey and basil. Set aside.
3.To cook, heat oil in a large, non-stick frying pan or wok set over medium-high heat. Add beef and stir-fry until lightly browned, from 1 to 2 minutes. Stir in bok choy and continue to cook just until wilted, from 1 to 2 minutes. Stir teriyaki mixture, then pour into pan. Reduce heat to medium. Cook, stirring often, until sauce has thickened, from 2 to 3 minutes. Stir in green onions. Serve immediately. Great over wide rice noodles or steamed rice with hot chili-garlic sauce for dipping.