Bring broth to a boil in a large, deep non-stick skillet over high heat; stir in orzo and reduce heat to medium-high. Cook according to package directions, stirring frequently, except DO NOT DRAIN.
Reduce heat to medium. Stir in green beans and tomatoes; cook 1 minute.
Arrange fish over orzo mixture; sprinkle with oregano and salt and pepper, if desired. Reduce heat to medium; cover and simmer 8 to 9 minutes or just until fish is opaque. Top fish with grated lemon peel before serving.