Place the diced potatoes in a large pot and cover with cold water. Add a pinch of salt and bring to a boil. Cook until the potatoes are tender, about 10-15 minutes. Drain and let cool slightly.
In a small saucepan, heat the vegetable oil over medium heat. Add the Szechuan peppercorns and fry for about 1-2 minutes until fragrant. Remove from heat and let cool slightly.
In a large mixing bowl, combine the chili oil, soy sauce, rice vinegar, sesame oil, and sugar. Add the cooled Szechuan oil mixture and stir well.
Add the cooked potatoes to the dressing and toss gently to coat.
Stir in the chopped green onions and cilantro. Season with salt to taste.
Cover and refrigerate for at least 30 minutes to allow the flavors to meld. Serve chilled or at room temperature.