-- 2 Tbs. + 1/4 c. olive oil
-- 1 large onion (~8 oz.), sliced 1/8" thick
-- 1 lbs. red-skinned potatoes, peeled and c ut into 1/8" slices
-- 6 large eggs
-- salt and pepper
Heat 2 Tbs. olive oil in a large skillet over medium heat. Add the onion and salt and pepper to taste. Cook until the onions are soft and golden, reducing the heat as they cook, about 20 mins. Remove to a large bowl. Heat in the same skillet 1/4 c. olive oil over high heat. Add the potatoes and cook until golden brown, 10-12 mins. Reduce heat to med.-high if the oil gets too hot and smoky. Remove the potatoes with a slotted spoon to paper towels to drain. Set aside the pan with the oil in it.
Add to the onions eggs, 1/2 tsp. salt and black pepper to taste. Sprinkle the potoates with salt and pepper to taste. Add the potatoes to the egg mix, and toss to coat the slices well.
Return skillet to high heat to heat the remaining oil in the pan. When hot, add the egg mix and immediately reduce the heat to low. Let the omelet cook for 3-4 minutes, undisturbed, until the bottom is golden and the eggs are 2/3 - 3/4 set. Shake the pan from time to time to make sure the omelet does not stick.
Place a lightly oiled large heatproof plate upside down over the omelet and flip the skillet to turn the omelet over. Slide the omelet back into the pan to cook the second side. COok until golden and set, 2-3 mins. more. Shake the omelet loose from the pan and slide onto a clean plate. Cut into 6 wedges and serve hot or at room temp.
[taken from Joy of Cooking: All About Breakfast & Brunch by Irma S. Rombauer, Marion Rombauer Becker, Ethan Becker]