Tear the spinach into 1 1/2-inch pieces, discarding any tough thick stems towards the bottoms. Heat the vegetable oil in a hot wok and saute the garlic over high heat until slightly browned. Add the spinach and toss for 1 minute. Add the oyster sauce, soy beans and palm sugar and toss for 1 minute more. Transfer to a serving plate, garnish with the chiles and serve.