Makes 6 servings
Although Americans think of the tortilla as the wrapper for a taco or a burrito, Spaniards use the term to refer to flavorful egg dishes like this one, which is a cousin to the Italian frittata. Serve it hot or make it up to a day ahead (wrap it in plastic wrap and refrigerate), and then serve at room temperature.
Here the onions caramelize and become sweet as they cook. You can add other vegetables, too, such as thinly sliced potatoes.
¼ cup olive oil, divided
1 pound yellow onions, finely chopped
Salt and freshly ground pepper to taste
Fresh sage leaves or fried sage leaves for garnish
Heat 2 tablespoons of the olive oil in a large skillet over medium heat. Add the onions; cover and cook for about 15 minutes, stirring once halfway through. Reduce the heat to low; cook, covered, stirring occasionally, until the onions are very soft and golden, about 45 minutes. Let cool for 10 minutes.
Whisk together the eggs, salt, and pepper in a medium bowl. Stir in the onions.
Heat the remaining 2 tablespoons oil in a 10-inch skillet over medium heat; add the egg-onion mixture. Cook undisturbed for 3 minutes, then occasionally loosen the edges with a spatula to allow the uncooked portion to flow to the bottom of the pan until the eggs are almost set, about 10 minutes.
Place a plate over the top of the skillet. Holding them firmly together, invert the plate and skillet so the tortilla falls onto the plate. Slide the tortilla back onto the skillet, browned side up. Cook until the bottom is browned and the inside is cooked through but still moist, about 5 minutes.
Slide the tortilla onto a serving plate and cut into wedges. Serve hot, warm, or at room temperature. Garnish with sage leaves.