Bacalao is the Spanish word for a slab of boneless, skinless dried salt cod. The filets -- long, snowy looking things -- pop up in all the Mexico City grocery stores and markets during Christmastime. I had eaten fried bacalao a few times in Spain, but I'd never tried it the Mexican way, which combines tomatoes, onions, green olives, chiles and garlic to make a kind of fishy stew. The idea of cooking with salted fish intrigued me, in a Laura Ingalls Wilder kind of way. (Remember how her family used to eat salt pork?) So I picked out a rather large, one-and-a-half pound piece at Mercado de la Merced a few weeks ago, and asked the vendor for cooking instructions. She gave me a detailed list, which I wrote down in my moleskine. You can see them below, at the bottom of the page. To check the recipe's veracity, I flipped through Diana Kennedy and Rick Bayless, who currently comprise the bulk of my Mexican cooking library. Luckily, "Rick Bayless's Mexican Kitchen" had a recipe that mirrored the vendor's instructions almost exactly. I decided I'd whip up a mixture of his dish and the market vendor's. Unfortunately, amid attending a friend's posada and throwing my own tamalada, I didn't plan very well. Bacalao must be de-salted before cooking, which means it has to sit in a dish of water for several hours. Once mine was sufficiently salt-free, I was up to my ears in cornhusks. I wasn't ready to cook it, so I stuck it in the freezer for a few days and prayed. Surprisingly, it turned out great. The fish was hearty and toothsome, but not tough. And the tomato-onion mixture was the perfect foil -- light, spicy, and with a kick of saltiness from the olives. I added small red potatoes, too, although you can also serve it with rice. The dish looks complicated, but really, it's not difficult at all. We've been eating the leftovers over the past few days and it only gets better with time. I think this might be another new Christmas tradition, along with figgy pudding. Recipe below. Christmas Bacalao Inspired by a vendor at Mercado de la Merced, and Rick Bayless's Mexican Kitchen Serves 6 to 8 as a light dinner Bacalao is sold all over Mexico City around Christmas time, and once you buy it, it keeps for up to two months, or so says the lady at Mercado de la Merced. To cook it, start preparing the day before. Place the bacalao in a dish and cover with cold water. Change out the water every few hours, until the bacalao is sufficiently less salty. You can also freeze it for a few days, if you totally lose track of time. Also, it's not the traditionally Mexican thing to do, but I'd serve this with a fresh green salad sprinkled with panela cheese, or any other mild fresh farmer's cheese to contrast with the bold flavors of the fish. A big hunk of crunchy bread would go well, too. It's best to use the freshest, ripest tomatoes possible. Only about half of mine were truly ripe, and the dish still turned out well, but lacked a big bright punch of tomato flavor. Next time I may try slow-roasting a few tomatoes, and adding that into the mix as well. Ingredients 1 1/2 pounds of bacalao (salted, dried cod) 1 1/2 pounds small red potatoes 2 pounds ripe tomatoes 1 large white onion, diced 3 garlic cloves, peeled and minced 1/2 cup flat-leaf parsley 3/4 cup green olives, either left whole, or pitted and sliced 6 pickled guerito chiles, or more if you like it spicy 1/2 teaspoon thyme Prepare the cod the day before by placing it in a dish of cold water. Change out the water every few hours, until the cod no longer tastes overly salty. If you live in a high altitude, like me, you'll want to prepare the potatoes next, because they take forever to cook. I like to save time by zapping them in the microwave. Place them in a microwaveable bowl and toss with 1 teaspoon salt. Cover tightly with plastic wrap and cook at 5 minute intervals, on high, until they're tender. Leave them in the microwave, covered, to keep warm. Roast your tomatoes either under the broiler or on a comal, until they're blackened and blistered in spots. Remove the skins once they're cool enough to handle, and place them in a blender. Puree until you no longer see any thick pieces of tomato. Heat a few glugs of olive oil over medium heat in a large, 12-inch skillet, or a enameled dutch oven. Add your onion and cook until softened, about five minutes. Then add garlic and cook until aromatic, about 30 seconds to a minute. Add the tomato mixture, stir, and cook the whole thing until it's reduced and thick, about 15 to 20 minutes, depending on your altitude. While the tomato mixture is cooking, place your newly salt-free bacalao in a sauce pan, and cover it with water. Bring to a boil, cover, and simmer the fish for about 5 minutes. Drain and set aside. Once your tomato sauce has thickened, add the parsley, olives, guerito chiles, and thyme. [Note: The Mercado de la Merced market vendor also says to add carrots here. I didn't have any in the house so I didn't use them, but a touch of sweetness from the carrots would make a nice addition.] Stir in enough water to create a soupy broth, and then add your fish into the pan, nestling it inside so it's covered by the other ingredients. Simmer for an hour, adding more water if fish looks too dry. Bayless's recipe says the fish should break up into chunks, but mine didn't entirely do that, and it still tasted fine. When fish is done cooking, add your potatoes to the pot and stir. Serve in heaping spoonfuls on a plate, and garnish with parsley. Sing "Feliz Navidad" as you eat.