Cook the long beans in boiling water until tender crisp, about 2 minutes. Transfer the beans with a slotted spoon to an ice bath until cool. Drain. Set aside.
Heat the oil in a wok or skillet over medium heat. Add the green beans and stir fry for 2 minutes. Add the garlic, hoisin sauce, and oyster sauce and stir fry for 30 seconds.
Dish out and garnish with roasted cashews. Serve immediately with steamed rice.