Finely cut onions. Mince garlic. Chop cabbage into small squares. On medium heat, place oil in a wide, flat pan (or use a wok). Add onions, cooking for 2 minutes. Add cabbage and garlic. Season with salt and pepper, mixing occasionally. If your skillet is very small, you might have to add a little cabbage at a time until the leaves shrink down.
In the mean time, boil noodles according to package instructions. Drain and set aside.
Cook cabbage mixture until leaves are wilted. Combine noodles and cabbage mixture together. Mix well and serve immediately.