Cut the napa cabbage into 1 1/2″ wide strips. Discard the end of the stem. Keep the thicker stems on one side of the cutting board, and the thin leafy leaves on the other side.
Heat a wok or large saute pan over medium-high heat. Add the cooking oil and when hot, add the ginger and the garlic. Cook for 15 seconds, until fragrant.
Add the thick napa cabbage stems, stir fry for 30 seconds. Pour in the soy sauce, broth (or water), and pinch of sugar. Add in the rest of the leafy leaves into the pan. Cover and cook for 2 minutes until cooked through. The thick stems should still be a bit crunchy, the leaves softened.