In a small bowl, combine cornstarch and broth until smooth. Stir in the soy sauce, hoisin sauce and sesame oil; set aside., In a large nonstick skillet or wok, stir-fry broccoli in oil until crisp-tender. Add the onions, garlic and ginger; stir-fry until vegetables are tender, 3-4 minutes. Add shrimp; stir-fry until shrimp turn pink, 4-5 minutes longer., Stir cornstarch mixture and add to the pan. Bring to a boil; cook and stir until thickened, about 2 minutes. Serve with rice. If desired, garnish with additional green onions.