Step 1
If using unblanched (skin-on) peanuts, place in a medium bowl and pour in water to cover. Let soak at least 6 hours and up to 12 hours. Drain peanuts, then rub off skins with paper towels if needed.
Step 2
Arrange peanuts on a rimmed baking sheet and freeze at least 2 hours and up to 12 hours (this will dehydrate the nuts so that they crisp faster when fried). If using blanched peanuts, skip the soaking and freeze directly.
Step 3
Place frozen peanuts in a wok or medium pot and pour in oil to cover by ¼”. Bring to a simmer over medium heat and cook until peanuts are golden brown and float to the surface, 15–20 minutes. Using a spider or slotted spoon, transfer to paper towels to drain. Let oil cool. Transfer all but 1 tsp. oil to an airtight container; save for another use.
Step 4
Add sliced chiles, whole chiles, and whole Sichuan peppercorns to skillet with oil and heat over medium-high, stirring constantly, until fragrant, about 2 minutes (don’t let the chiles brown—you want them to stay red). Mix in peanuts, salt, sugar, Five-Spice Powder, ground Sichuan peppercorns, and white pepper (if using). Transfer to a small bowl; let cool.
Step 5
Do Ahead: Peanuts can be made 3 days ahead. Store airtight at room temperature.