Place the potatoes in a medium saucepan and add enough cold water to cover. Bring to a simmer and cook until just tender, about 5 minutes. Alternatively, place them in a glass bowl, cover with plastic, then microwave on high until tender, about 3 to 5 minutes.
Meanwhile, heat the oven to 350 degrees. Coat a 9-inch glass pie plate with cooking spray.
Spread the potatoes over the bottom of the pie plate and season with salt. Spoon the salsa over the potatoes.
In a mixing bowl, whisk together the eggs, egg whites, flour, oregano and pepper until smooth. Stir in the cheese and scallions.
Pour the mixture over the potatoes and salsa. With a fork, gently stir the mixture so the cheese and potatoes are evenly distributed. Bake the frittata for 30 to 35 minutes, or until it is set at the center and golden on top. Slice into wedges to serve.