Put the sliced lotus root into vinegar water as you slice it, as described above. Drain well just before cooking.
Heat up a large frying pan with the oil. Add ginger and garlic, and stir fry until the oil is very fragrant.
Add the drained lotus root slices in a single layer. Cook until the lotus root slices start to change color - they turn a bit translucent looking. Turn over and cook a couple more minutes.
Add the chili pepper and green onions, and stir-fry. Add the sesame seeds, pepper, soy sauce and sesame oil.
The lotus roots should get a bit caramelized from the soy sauce. Serve hot or cold. This is very nice for bento.