Cemitas De Lengua

Ingredients

• 1 cow or veal tongue, about 1 1/2 pounds
• 2 medium onions
• Kosher salt and freshly ground black pepper
• 3 tablespoons vegetable or canola oil
• 1 can black beans, drained, 3 tablespoons liquid reserved
• 4 to 6 cemita rolls, halved and lightly toasted when ready to serve
• 2 to 3 ripe avocados
• 4 ounces fresh Mexican cheese, such as Oaxaca cheese
• 1 tomato, thinly sliced
• A few leaves iceberg lettuce, shredded
• 1/2 cup crema or sour cream

Directions

1. Put the tongue in a medium saucepan. Cut 1 onion in half and drop it in with the tongue, then pour in enough cold water to cover everything and add plenty of salt. Set the pan over high heat and bring it to a boil, then turn the heat all the way down. Cover the pan and let it cook until the tongue is fully tender, about 2 1/2 hours, adding more water along the way if the level gets low.
2. Move the tongue to a cutting board, then throw away the cooking liquid, or keep it if you want it for something else. Pull off the outer membrane from the tongue carefully and discard it. Cut the tongue into 1-inch pieces.
3. Chop the remaining onion finely. Warm 1 tablespoon oil in a large skillet over medium heat until it shimmers, then add the onion. Cook, stirring often, until the onion has softened without taking on color, about 5 minutes. Stir in the beans with 3 tablespoons liquid and keep cooking, stirring often, until everything is hot. Take the skillet off the heat and set it aside. Mash the beans with a potato masher, food mill, or food processor until you have a chunky puree. Add salt and pepper to taste, scrape the beans into a bowl, and clean out the skillet.
4. Pour the remaining 2 tablespoons oil into the skillet and heat it over high heat until shimmering. Add the tongue and leave it alone until the first side is deeply browned, about 2 minutes. Toss the pieces and keep cooking until they are browned all over, about 10 minutes total. Season with salt and pepper to taste.
5. For assembly, spread a few spoonfuls of the black bean mash over the bottom half of each toasted roll. Pile on the tongue, then add avocado, lettuce, tomato, and cheese. Spoon crema over the fillings, cap each sandwich with its top bun, and serve immediately.