Prepare the chiles and set aside.
Then, in a medium saucepan, boil the potatoes in water to cover until barely tender.
Cool under running water.
Peel, and cut into 3⁄4-inch pieces.
Set aside.
Remove the seeds and veins from the chiles and cut them into thin strips.
Set aside.
In a large nonstick skillet, heat the oil over medium heat and cook the onion until softened, 3 to 4 minutes.
Add the potatoes, chile strips, salt, and pepper.
Raise the heat to medium-high and cook until the potatoes are lightly browned, stirring frequently, so they don't stick, about 10 minutes.
Add more oil, if needed.