Tortilla de patatas, a thick Spanish omelet of potatoes, eggs, and onions, is one of my most favorite dishes ever. Considered the ultimate comfort food, this dish is everywhere in Spain: Every restaurant, tapas bar, and roadside tavern serves it. It can be eaten for breakfast, lunch, or dinner, served with bread and tomato sauce, salad, and sometimes, mounds of mayonnaise. I love it with mayonnaise in the warmer months, and with hot tomato sauce in the winter. It can be a full meal between toasted baguettes, or cut into squares to serve as a tapa. I always have it in my fridge when I have houseguests as a last-minute change-of-plans lunch. After peeling and chopping thousands of potatoes, I now make it with store-bought shredded potatoes. I know Spaniards will scream in horror, but a clever shortcut without giving up the flavor is a good thing in my kitchen. …