Potatoes are a relatively new staple crop in the Szechuan region. Cut the potatoes for this stir-fry into threads, and sauté just a few minutes so they're still a bit crunchy. Waxy white potatoes stay firm and hold their shape when cooked. Use a mandoline or food processor fitted with a julienne blade to quickly cut the potatoes.
Soak potato in cold water 5 minutes. Drain and pat dry.
Heat oil in a large nonstick skillet over medium-high heat. Add onions, ginger, garlic, and chiles; stir-fry 30 seconds. Add potato; stir-fry 4 minutes or until crisp-tender. Add vinegar mixture, and stir-fry 1 minute. Serve immediately.