SPICY BEEF WITH SHRIMP AND BOK CHOY

Ingredients
1/4 cup lemon juice (see Ingredient note)
1 1/2 tablespoons oyster-flavored sauce
2 teaspoons cornstarch
4 teaspoons canola oil, divided
3/4 pound sirloin steak, trimmed of fat, cut in half lengthwise and thinly sliced
1/4 teaspoon crushed red pepper
10 raw shrimp (21-25 per pound), peeled, deveined and chopped
1 pound bok choy, preferably baby bok choy, trimmed and sliced into 1-inch pieces

Directions
1. Whisk lemon juice, oyster sauce and cornstarch in a small bowl until the cornstarch is dissolved.
2. Heat 2 teaspoons oil in a large nonstick skillet or wok over medium-high heat. Add beef and crushed red pepper to taste; cook, stirring, until the beef begins to brown, 1 to 2 minutes. Add shrimp and continue to cook, stirring, until the shrimp is opaque and pink, 1 to 2 minutes. Transfer the beef, shrimp and any juices to a plate.
3. Heat the remaining 2 teaspoons oil over medium-high heat in the same pan. Add bok choy and cook, stirring, until it begins to wilt, 2 to 4 minutes. Stir in the cornstarch mixture. Return the beef-shrimp mixture to the pan and cook, stirring, until heated through and the sauce has thickened slightly, about 1 minute.