Preheat oven to 350℉/180℃. Grease a 8 or 9-inch square baking dish with a tablespoon oil.

In a bowl, lightly beat the eggs with salt and pepper, remaining 4 tablespoons oil, and onion.

Peel and grate the potatoes (you may use a food processor) and stir them quickly into the egg mixture (if you don’t do it quickly, they will tarnish).

Pour into prepare pan and bake for 1 hour. Turn heat to 450℉/230℃ for 5-10 minutes, or until crispy and browned. Serve hot.