Place broccoli in a large saucepan; add 1 inch of water. Bring to a boil. Reduce heat; cover and cook for 5 to 8 minutes or until crisp-tender. Meanwhile, in a small, heavy saucepan, heat chicken broth and butter until butter is melted. Combine cornstarch and water until smooth; stir into broth mixture. Bring to a boil; cook and stir 2 minutes longer or until thickened and bubbly. Remove from heat. Stir in a small amount of hot mixture into egg yolks; return all to pan, stirring constantly. Bring to a gentle boil; cook and stir 2 minutes longer. Remove from heat. Gently stir in lemon juice and peel. Drain broccoli; serve with sauce. Yields 10 servings with 1¼ cups sauce.