1/4 cup extra-virgin olive oil
1 1/2 lb Yukon Gold potatoes (about 5), peeled and halved lengthwise, then cut crosswise into 1/4-inch-thick slices
1 large onion, halved lengthwise, then sliced lengthwise (1/4 inch thick)
3/4 teaspoon dried oregano, crumbled
1/2 teaspoon salt
1/4 teaspoon black pepper
3 tablespoons finely grated Parmigiano Reggiano

Heat oil in a 12-inch nonstick skillet over moderately high heat until hot but not smoking, then add potatoes, onion, oregano, salt, and pepper and reduce heat to moderate.

Cook, covered, stirring and turning potatoes over occasionally, until almost tender, about 10 minutes. Remove lid and cook, stirring and turning potatoes over 3 or 4 times, until browned and crusty, 8 to 10 minutes more.

Add salt and pepper to taste, then transfer to a shallow bowl and sprinkle with cheese.

Makes 4 servings.