Heat the oils and soy sauce and sugar in a skillet that has a lid. Add the green beans, stir to coat, cover, and cook over medium high heat for 5 minutes or so, stirring now and then.
Uncover the skillet and add the water and garlic. Stir and increase the heat a bit so you can stirfry the beans, stirring frequently. Cook until they reach the point of tenderness you like. You want the skillet to be moist enough to not burn them, yet not so moist that they don't get any browning. Add a small bit of water if necessary.
Put the cooked beans in a serving dish and sprinkle the sesame seeds on top.