Step 1

Begin by preparing the beef tongue. Rinse it thoroughly under cold running water and pat it dry with paper towels. Place the tongue on a cutting board and use a sharp knife to trim away any excess fat or gristle.

Step 2

Next, prepare the aromatics for the cooking liquid. Peel and halve two small onions, and cut two heads of garlic in half crosswise. Gather eight bay leaves, two teaspoons of salt, and two teaspoons of black peppercorns.

Step 3

Fill a large pot with five quarts of water and place it over high heat. Add the onions, garlic, bay leaves, salt, and black peppercorns to the pot. Bring the water to a rolling boil.

Step 4

Once the water is boiling, gently add the beef tongue to the pot. Make sure the tongue is completely submerged in the cooking liquid. Reduce the heat to low to maintain a gentle simmer.

Step 5

Cover the pot with a lid and let the beef tongue simmer for 3.5 hours or until it is tender. Check on the tongue occasionally, and add more water to the pot if necessary to ensure that the tongue remains covered.

Step 6

Once the beef tongue is cooked, use tongs to carefully remove it from the pot and place it on a cutting board. Let the tongue cool for about 15 minutes, or until it is cool enough to handle.

Step 7

While the beef tongue is cooling, prepare the Creamy Green Salsa. Start by peeling and pitting two ripe avocados, and removing the husks from six tomatillos. Roughly chop the cilantro, and peel two garlic cloves. Remove the seeds from two jalapeño peppers for a milder salsa, or leave them in for a spicier version.

Step 8

Add the avocados, tomatillos, cilantro, garlic, and jalapeño peppers to a blender or food processor. Squeeze the juice of three lemons into the blender, and season the mixture with salt to taste. Blend the ingredients until smooth.

Step 9

Once the beef tongue has cooled, remove the outer skin or membrane from the tongue using a sharp knife. Cut the beef tongue into thin slices or shred it with a fork.

Step 10

Warm the yellow corn tortillas in a dry skillet over medium heat, flipping them occasionally until they are soft and pliable.

Step 11

To assemble the tacos, place a few slices of beef tongue onto each tortilla. Top the meat with a sprinkle of chopped onion and cilantro. Squeeze a wedge of lime over each taco, and spoon a dollop of the Creamy Green Salsa onto the top.

Step 12

Serve the Beef Tongue Tacos with Creamy Green Salsa immediately, and enjoy!