In a Dutch oven or large saucepan, heat oil over medium-high. Add the chiles and onion and cook, stirring often, until the vegetables are softened, 5 minutes. Add the pork; season with salt and pepper and cook, stirring often, until browned, 5 minutes.
Add the potatoes, salsa and 2 cups water; bring to a boil. Reduce the heat to medium, partially cover and simmer, stirring the chili occasionally, until the pork is tender, about 40 minutes. Season, divide among bowls and garnish with the cheese and cilantro.