In a small bowl, whisk together the soy sauce, vinegar, sugar, and chili flakes. Set aside. Place 1/4 cup water in a large skillet and bring to a boil over high heat. Add the green beans, cover the pan, and cook until the beans are crisp tender, 3 to 4 minutes. Uncover, and drain any water that remains in the pan. Add the oil, ginger, and garlic to the beans in the skillet and cook over medium-high heat, stirring frequently, until the beans are lightly browned, about 2 minutes. Don't let the garlic burn. Add the soy mixture to the pan and cook, stirring constantly, until the sauce thickens and glazes the beans, about 2 minutes.