1 large yellow onions
3 pounds Russet or Idaho potatoes, peeled
1/3 c potato or corn starch
2 tsp salt
Lots of freshly ground black pepper
3 large eggs
5 tbsp olive oil
Heat oven to 350°F.
With a food processor: Blend onions in food processor with regular blade until finely ground. Switch to grating blade and grate potatoes — I like to do this one their sides, for the longest strands.
Place onions and potatoes in a large bowl. Sprinkle salt, pepper and starch evenly over potatoes and toss together evenly coating strands. Break eggs right on top and work them into the strands, evenly coating the mixture.
Heat a 1/4 cup oil or fat in a 10-inch cast-iron skillet over high heat until very hot. Pour potato-egg mixture into pan carefully and spread evenly in pan. Drizzle with last tablespoon of oil.
Bake in heated oven for 75 to 80 minutes, until browned on top and tender in the middle.
Serve in squares, either right from the skillet or unmolded onto a platter.