Heat a large, heavy skillet with a tight-fitting lid. When the pan is hot, add the oil and heat it for 30 seconds. Add the ginger, garlic, pepper flakes, and green beans and cook over high heat for 1 minute, stirring constantly. Add 1⁄2 cup of water and a generous pinch or two of salt. Cover the pan and steam for 6 minutes, or until beans are almost fully tender. Check on the water once or twice; if more is needed, add 1⁄4 cup. Add the hoisin and soy sauces and stir. Cook, uncovered, until the water evaporates and the sauce coats the beans thickly. Serve hot.