1 1/2 cups thinly sliced red onion
1/4 teaspoon freshly ground pepper
7 large eggs, beaten
1 1/2 cups chopped zucchini
2/3 cup pearl-size or baby fresh mozzarella balls
2 tbsps extra-virgin olive oil
1/2 tsp salt
1/4 cup thinly sliced fresh basil
3 tbsps chopped soft sun-dried tomatoes
Position rack in upper third of oven; preheat broiler.
Heat oil in a large broiler-safe nonstick or cast-iron skillet over medium-high heat.
Add onion and zucchini and cook, stirring frequently, until soft, 3 to 5 minutes.
whisk eggs, salt and pepper in a bowl.
Pour the eggs over the vegetables in the pan.
Cook, lifting the edges to allow uncooked egg from the middle to flow underneath, until nearly set, about 2 minutes.
Arrange mozzarella and sun-dried tomatoes on top and place the skillet under the broiler until the eggs are slightly browned, 1 1/2 to 2 minutes.
Let stand for 3 minutes.
Top with basil.
To release the frittata from the pan, run a spatula around the edge, then underneath, until you can slide or lift it out onto a cutting board or serving plate.
Cut into 4 slices and serve.