Heat oil over medium-high heat in a 10 sauté pan. Add potatoes and onions and cook, lifting and turning, until potatoes are soft but not brown, about 20 minutes. Beat eggs in a large bowl until pale yellow. Transfer sautéed potatoes and onions with a slotted spoon to beaten eggs. Reserve oil. Heat 1 tbsp. reserved oil in the same pan over medium heat. Add egg and potato mixture, spreading potatoes evenly in the pan. Cook uncovered until the bottom is lightly browned, about 3 minutes. Gently shake pan so tortilla doesnt stick, then slide a spatula along edges and underneath tortilla. Place a large plate over pan and quickly turn plate and pan over so tortilla falls onto plate. Add 1 tsp. reserved oil to pan, slide tortilla back in (uncooked side down), carefully tuck in sides with a fork, and continue cooking over medium heat until eggs are just set, about 3 minutes. Cut into wedges and serve at room temperature. SERVES 4 – 8 This classic Spanish dish can be served for breakfast, cut in cubes for tapas, or as a summer lunch with a bowl of gazpacho. A quick note: Add the potato mixture while its hot enough to start cooking the eggs but not so hot as to soufflé them.