Preheat your oven to 400°F (200°C).
Toss the diced zucchini, red bell peppers, and red onion with 1 teaspoon of olive oil and a pinch of sea salt on a large baking sheet.
Roast the vegetables for 15 minutes until they are tender and slightly charred at the edges.
While the vegetables roast, whisk together the large eggs, egg whites, chopped parsley, dried oregano, sea salt, and black pepper in a medium bowl until well combined.
Heat the remaining 1 teaspoon of olive oil in an 8-inch oven-safe non-stick skillet over medium heat.
Add the roasted vegetables to the skillet in an even layer, then pour the egg mixture over them.
Cook undisturbed for 3 minutes until the bottom and edges are set, then sprinkle the crumbled feta cheese evenly over the top.
Transfer the skillet to the oven and bake for 8 to 10 minutes until the center is firm and the top is lightly golden.