Prepare Green Beans: Cut green beans in half. Boil water with salt and cook green beans for about 7 minutes until tender.
Slice Garlic and Onion: While beans are cooking, slice the garlic and onion.
Drain Beans: Once green beans are cooked and vibrant green, drain them and reserve 1/2 cup of the bean-cooked water.
Stir-Fry: Heat cooking oil in a pan, add garlic, and then add green beans, reserved bean-cooked water, soy sauce, and onion. Stir continuously until the water has evaporated.
Final Touch: Add sesame oil towards the end of cooking and mix well.