Heat a skillet over medium high heat. Add oil and onion and sauté 2 minutes. Add cabbage sautéing it until it wilts, 3 to 5 minutes.
Add vinegar to the pan and turn the cabbage in it. Sprinkle sugar over the cabbage and continue sautéing.
Season with salt and pepper and reduce heat a bit. Let cabbage continue to cook 10 minutes or until ready to serve, stirring occasionally.