Preparation Place cornstarch in small bowl. Gradually add broth, stirring until cornstarch dissolves. Mix in lemon juice and peel. Heat 2 teaspoons oil in large non-stick skillet over medium-high heat. Season beef with salt and generous amount of pepper. Add beef to skillet and stir-fry until just brown, about 3 minutes. Using slotted spoon, transfer beef to plate. Add remaining 2 teaspoons oil to skillet. Add vegetables; stir-fry until bright in color and just beginning to soften, about 3 minutes. Stir broth mixture quickly to re-blend; add to skillet. Add beef and any collected juices. Cook until sauce thickens and all vegetables are crisp-tender, stirring frequently, about 5 minutes. Transfer to bowl. Sprinkle with cilantro.
Preparation Place cornstarch in small bowl. Gradually add broth, stirring until cornstarch dissolves. Mix in lemon juice and peel. Heat 2 teaspoons oil in large non-stick skillet over medium-high heat. Season beef with salt and generous amount of pepper. Add beef to skillet and stir-fry until just brown, about 3 minutes. Using slotted spoon, transfer beef to plate. Add remaining 2 teaspoons oil to skillet. Add vegetables; stir-fry until bright in color and just beginning to soften, about 3 minutes. Stir broth mixture quickly to re-blend; add to skillet. Add beef and any collected juices. Cook until sauce thickens and all vegetables are crisp-tender, stirring frequently, about 5 minutes. Transfer to bowl. Sprinkle with cilantro.