Spanish Potato Omelet with Roasted Peppers (Tortilla de Patatas con Pimientos Asados)

“Spaniards eat tortilla de patatas at all hours of the day; hot from the pan for supper or lunch, at room temperature as a midmorning snack, or washed down with a glass of wine at a tapas bar,” writes Maricel Presilla in “Peppers of the Americas.” “For long car trips and picnics, this is the food they are most likely to bring along …

“Making a great tortilla de patatas takes a bit of practice, as you need to flip the tortilla to cook it on both sides. It also requires a grassy olive oil and the freshest, most flavorful eggs you can find.

“My recipe is heavy on potatoes and roasted peppers, but you can reduce the amount for an eggier omelet.” Makes 4 to 6 servings as an appetizer, and 6 to 8 as a main dish

1 pound (about 6 medium) hot green peppers for roasting, such as poblano or NuMex peppers

2 pounds (5 large) russet potatoes, peeled and cut into 1⁄4-inch slices

1 pound yellow onions, cut into 1⁄2-inch rings

1 1⁄2 to 2 teaspoons salt

2 cups light olive oil, or a mixture of 1 cup corn or sunflower oil and 1 cup extra-virgin olive oil

8 large eggs, lightly beaten

Roast the peppers — here are three methods: Griddle-roasting: Heat a cast-iron skillet or a comal over medium-high heat until a drop of water sizzles on contact. Place the whole peppers on the hot surface and roast, turning occasionally with tongs, until they are blackened on all sides. The timing will depend on shape and size — a few seconds for small peppers; 1 minute or so for long skinny ones; and up to 3 minutes for large wrinkled ones.

Flame-roasting: Working with one pepper at a time, hold it with tongs over a gas burner or grill, turning it so it chars evenly.

Broiling: Position an oven rack so the peppers will be about 4 inches from the heat source. Set the whole peppers on a baking sheet, and when the broiler is hot, slide the pan into the oven. Turn them from time to time until they are blistered and charred all over.

Whichever method you use, immediately place the blackened peppers in a paper or food-safe plastic bag, close it tightly, and let them steam to loosen the skins. When they are cool enough to handle, after about 10 minutes, remove the skin with a paring knife or your fingers. Do not rinse them or you will lose some of the wonderful caramelized flavor.

Core, stem, seed, devein, and cut into 1-inch squares.

Place the potatoes and onions in a medium bowl. Add the salt and toss well to coat. Warm the oil in an 11-inch nonstick or well-seasoned skillet over medium-high heat. When the oil is rippling but not smoking, add the potatoes and onions. Lower the heat to medium, cover and cook, stirring occasionally, until potatoes are fork-tender and onions are soft and translucent, about 20 minutes. Add roasted peppers and cook about 5 minutes. Drain, reserving 2 tablespoons of the oil.

Transfer vegetables to a large bowl. Pour in eggs and stir gently with a rubber spatula to combine, being careful not to break up the potatoes. Return reserved oil to skillet over medium-high heat. Add egg mixture and cook until egg sets and separates completely from side of pan, about 3 minutes. Using a spatula, lift the tortilla and check the bottom; it should be golden. To cook the other side, remove the skillet from the heat, cover with a plate that is slightly larger in diameter than the skillet, and, holding both the skillet and the plate firmly with oven mitts, flip the tortilla onto the plate. Return the skillet to the heat and very gently slide the tortilla back into the skillet. Cook until completely set and golden, about 5 minutes more.

Using the spatula, gently slide the tortilla onto a serving plate. Serve warm or at room temperature, ideally the day it is made, though it can be eaten cold from the refrigerator or brought to room temperature. Store, tightly covered, in refrigerator up to 2 days.