- 3 tablespoons olive oil
- 2 small russet potatoes (about ¾ pound), peeled and thinly sliced
- 1 small onion, thinly sliced
- 9 large eggs
- kosher salt and black pepper
- 1 10-ounce package frozen chopped spinach, thawed and squeezed of excess liquid
- 4 ounces white Cheddar, grated (1 cup)
- 4 ounces thinly sliced deli ham, cut into 2-inch pieces
- 1 tablespoon red wine vinegar
- 1 teaspoon Dijon mustard
- 1 head red leaf lettuce, torn into bite-size pieces (6 cups)
- Heat oven to 400° F. Heat 2 tablespoons of the oil in a large ovenproof nonstick skillet over medium heat. Add the potatoes and onion and cook, tossing occasionally, until the potatoes are tender, 12 to 15 minutes.
- Meanwhile, in a large bowl, whisk together the eggs, ½ teaspoon salt, and ¼ teaspoon pepper. Mix in the spinach, Cheddar, and ham.
- Add the egg mixture to the skillet, stir once, and transfer the skillet to oven. Cook until the eggs are set, 12 to 14 minutes.
- Meanwhile, in a large bowl, whisk together the vinegar, mustard, the remaining tablespoon of oil, and ¼ teaspoon each salt and pepper. Add the lettuce and toss to coat. Serve with the frittata.