- Peel the potatoes and cut them into thin noodle-like strips using a julienne peeler or mandoline. Soak them in cold water for 10 minutes to remove excess starch. 
- Drain and pat the potato noodles dry with a clean towel. 
- Heat oil in a large skillet or wok over medium heat. Add the garlic and white parts of the green onion. Sauté until fragrant, about 30 seconds. 
- Toss in the potato noodles and stir-fry for 2–3 minutes until they begin to turn translucent and slightly tender. 
- Add chili oil, both soy sauces, sugar, and white pepper. Stir everything together to coat the noodles evenly. Cook for another 2–3 minutes. 
- Taste and add salt if needed. Remove from heat and toss in the green parts of the green onion. 
- Serve warm, topped with sesame seeds and chopped cilantro if using.