- 3 tablespoons olive oil
- 1 large onion, cut into ¼-inch pieces (2 to 2 ½ cups)
- 2 garlic cloves, finely chopped
- 2 medium russet potatoes, peeled and cut into bite-sized pieces
- 1 red bell pepper, cored, seeded, and cut into bite-sized pieces
- 4 ounces porcini or shiitake mushrooms, trimmed and sliced
- 2 links (about ¾ pound) turkey chorizo, quartered lengthwise and cut into 1⁄8-inch thick slices
- 10 to 12 eggs
- ¼ cup milk
- ½ to ¾ cup freshly grated Parmesan cheese, or a Parmesan/Romano blend
Pour the olive oil into a 12-inch nonstick ovenproof skillet, and tilt the pan to coat the bottom and sides. Heat the oil over medium-high heat until the oil ripples. Add the onion and garlic, stir to coat with the oil, and cook, stirring, for 7 to 10 minutes, or until translucent and softened.
Add the potatoes, toss to combine, and cook, stirring, for 5 minutes, or until the potatoes just begin to color. Add the bell pepper and cook, stirring, for about 3 minutes, or until softened. Add the mushrooms and cook, stirring, until they have exuded their liquid and it has evaporated. Add salt to taste.
Add the chorizo and cook, stirring, for about 4 minutes, or until browned. (If necessary, move the vegetables to the side of the skillet and move the skillet with the vegetables off the heat to prevent them from sticking while the chorizo cooks.)
Preheat the oven to 350 degrees F.
Beat 10 of the eggs in a large bowl until light yellow in color. Beat in the milk. Remove the skillet from the heat and pour the beaten eggs over the vegetables and chorizo. If there is not enough egg batter to come at least halfway up the sides of the ingredients in the skillet, beat the remaining 2 eggs and pour them over the ingredients to fill. (The vegetables and chorizo should not be completely submerged, but the surface should be fairly even.) Sprinkle the cheese over the frittata.
Cover the skillet and bake on the middle rack of the oven for 35 to 45 minutes, or until the eggs are cooked through and the potatoes can be easily pierced with the tip of a sharp knife. Ten to 15 minutes before the end of the cooking time, remove the cover to brown the cheese. Transfer the skillet to the table, cut the frittata into wedges, and serve from the skillet. Or let the frittata cool to room temperature and serve.