Soak cut broccoli in iced water for 15 minutes. (This preserves the crispness throughout the cooking.) In a wok, heat the oil and fry the garlic until it just changes color. Quickly add the broccoli from the bowl, witout draining, and stir-fry for 3 minutes. Cover the wok and turn heat to low. Simmer fo 5 minutes, or until broccoli is tender but still crisp. Uncover, stir in fish sauce, oyster sauce, sugar and shrimp. Stir until shrimp are heated htrough and sugar has dissolved. Serve with plain rice.