- 1-3/4 cups olive oil
- 1-3/4 lb. (about 5 medium) low-starch potatoes, such as Yukon Gold, peeled
- 2-1/4 tsp. coarse salt
- 12 to 14 oz. onions (2 to 3 medium), diced
- 5 medium cloves garlic, coarsely chopped
- 6 large eggs
- 1/8 tsp. freshly ground black pepper
In a 10-1/2-inch nonstick skillet that's at least 1-1/2 inches deep, heat the oil on medium high. While the oil is heating, slice the potatoes thinly, about 1/8 inch. Transfer to a bowl and sprinkle on 2 tsp. of the salt, tossing to distribute it well.
When the oil is very hot (a potato slice will sizzle vigorously around the edges without browning), gently slip the potatoes into the oil with a skimmer or slotted spoon. Fry the potatoes, turning occasionally (trying not to break them, although some will anyway) and adjusting the heat so they sizzle but don't crisp or brown. Set a sieve over a bowl or else line a plate with paper towels. When the potatoes are tender, after 10 to 12 minutes, transfer them with the skimmer to the sieve or lined plate.
Add the onions and garlic to the pan. Fry, stirring occasionally, until the onions are very soft and translucent but not browned (you might need to lower the heat), 7 to 9 minutes. Remove the pan from the heat and, using the skimmer, transfer the onions and garlic to the sieve or plate with the potatoes. Drain the oil from the skillet, reserving at least 1 Tbs. (strain the rest and reserve to use again, if you like) and wipe out the pan with a paper towel so it's clean. Scrape out any stuck-on bits, if necessary.
In a large bowl, whisk the eggs, 1/4 tsp. salt, and the pepper until blended. Add the drained potatoes, onions, and garlic and mix gently to combine with the egg, again trying not to break the potatoes.
Heat the skillet on medium high. Add the 1 Tbs. reserved oil. Let the pan and oil get very hot (important so the eggs don't stick), and then pour in the potato and egg mixture, spreading it evenly. Cook for 1 minute and then lower the heat to medium low, cooking until the eggs are completely set at the edges, halfway set in the center, and the tortilla easily slips around in the pan when you give it a shake, 8 to 10 minutes. At that point, you have choices. 1. You can get tricky and “flip” the tortilla using a plate and return it to the pan to finish cooking. Or, 2) you cover the cover the tortilla in the pan with a tight-fitting lid and finish cooking over low heat. Or, 3) easier still, you can place the uncovered pan with the tortilla in the broiler and allow to finish cooking there. You’ll know it’s done when the center starts to brown a bit.
Once fully cooked, let the tortilla stand for 10 minutes or so before serving.