Tortilla. Photo: formalfallcy @ Dublin (Victor)/Flickr

Like paella, tortilla española is a quintessential Spanish dish. Ubiquitous on tapas bar menus, the circular potato and onion omelet is also versatile. Add peppers (as above) or chorizo for color and texture, or follow the lead of Michael Fiorello, chef de cuisine at Chicago tapas bar Mercat a la Planxa, who loves tossing in jamón Ibérico or seasonal mushrooms.

While labor intensive, basic tortilla española (an original recipe is after the jump) is well worth the effort for its inimitable flavor and flexibility. Adapt this recipe to suit your own needs -- perhaps finish it on the stove top, perhaps in the oven, as done at Mercat a la Planxa. Fiorello agrees: "You can cook tortilla using many different techniques." No matter how you slice it, tortilla española is addictive. If you can wait this long -- and you ought not -- it will keep for a couple of days.

Recipe after the jump.
Don an apron. Slice one russet potato and half of a Spanish onion into 1/8-inch pieces. Let the potato slices rest in acidulated water to prevent discoloration. Fill an 8-inch nonstick pan (at least two inches deep) with enough extra virgin olive oil to reach the first knuckle of your index finger (careful!) and heat over a medium flame.

Before dropping the potatoes in the oil, press them dry with a cloth. Not doing so will result in an oil geyser. Cook the potato slices until they begin to blister, but before they brown. Reserve the oil. If the pan has brown bits, wash and dry thoroughly before returning some of the oil and adding the onions. Sweat the onions with salt and pepper to taste and remove.

In a large bowl, add the potatoes and onions along with four beaten eggs and season with salt and pepper. Add some of the remaining oil into the pan and pour in the mixture. Cook for ten minutes, or until the tortilla lifts easily away from the pan. Once the tortilla has set, place a plate over the pan and flip. Flip quickly. Ease the omelet back into the pan. Cook the underside for about eight minutes, until it is golden brown. Remove the tortilla to a wire rack or plate with paper towel to soak up any excess oil.

Garnish with chopped cilantro or fresh thyme. Fight for seconds.