A frittata falls somewhere between an over-sized latke and an omelet. It will feed 6 to 8 people.
3 teaspoons cottonseed oil, divided
1 small onion, thinly sliced
1 clove garlic, crushed
1 tomato, (peeled, if it your custom to do so) seeded and chopped, divided
2 small cooked potatoes cut into 1/2-inch dice
1 medium zucchini, peeled or not, sliced into rounds ¼” thick
1/2 teaspoon salt
1/2 teaspoon freshly ground pepper, plus more to taste
4 large eggs
4 large egg whites
2 tablespoons chopped, checked scallions
Preheat the broiler. Heat 2 teaspoons of oil in a large, ovenproof, nonstick skillet over medium heat. Add onion, garlic, and half of the tomato; cook, stirring, until the onion is limp, about 8 minutes.
Add the potatoes and cook, stirring, until they start to brown, about 4 minutes. Add zucchini and cook until heated through. Remove the vegetables from the pan; season with salt and pepper.
Wipe out the pan, brush with the remaining 1 teaspoon oil, and return it to low heat.
Lightly whisk whole eggs and egg whites in a medium bowl. Add the vegetables to the egg mixture and pour into the pan, gently stirring to distribute the vegetables. Cook over low heat until the underside is light golden, 5 to 8 minutes.
Place the pan under the broiler and broil until the top of the frittata is puffed and golden brown, 1 to 2 minutes. Loosen the frittata and slide it onto a platter. Garnish with scallions and the remaining chopped tomato.
Slice in wedges and serve immediately.