Preheat the oven to 400 Degrees F. Spread the fries on a baking sheet and bake until golden brown and crisp, about 15 minutes.
While the fries bake, heat 1 tablespoon of oil in a large nonstick ovenproof skillet over medium heat. Add the onion and a pinch each of salt and pepper and cook, stirring occasionally, until golden brown and tender, about 5 minutes. Transfer to a large bowl, cool slightly, then stir in the eggs and fries.
Wipe out the skillet and coat with the remaining tablespoon oil. Heat over medium heat, then add the egg mixture. When the edges have set, transfer to the oven. Bake until set in the center, about 10 minutes. Cool slightly, then slide out of the pan and cut into wedges.