What is known in Mexico as barbacoa is totally different than American barbecue. Barbacoa is an ancient cooking technique that natives in Mexico used thousands of years ago and it's still widely used today.
Large pits are dug in the ground, then lined with mesquite wood and volcanic rocks. These are lit and when they become red coals, they're moved towards the edges of the pit and a large stockpot of water and vegetables is placed on the bottom of the pit. A grill is placed over the pot and then it is lined with maguey leaves (a type of agave plant).
The chunks of meat (goat, beef, sheep, or pork) are seasoned and wrapped in more maguey leaves, covered with more leaves, and then the whole pit is covered with a cloth and finally, dirt. The meat is cooked slowly overnight (12 hours) and in the morning the most succulent meat emerges. Besides the meat, there's consomé, the delicious broth that is created with the juices that drip from the meat into the stockpot at the bottom of the pit.
Though it would be fun to have a pit in the back yard, it's not practical and it would likely violate city laws. Instead, this recipe is made in a slow cooker but tastes almost like regular barbacoa.
In northern Mexico it is traditional to cook the head of the cow. None of it is wasted (brains, eyes, cheeks, tongue) and it all tastes heavenly. The meat is so tender, it falls apart. My favorite part is the tongue. You can find beef tongue in many grocery stores or ask your butcher to get one for you. A regular size beef tongue will feed at least six people.
These tacos de barbacoa are usually eaten for breakfast, like the real barbacoa, it's served as soon as it's done cooking, and that's early in the morning. All you need are fresh corn tortillas, a mix of chopped onion and cilantro, a squeeze of lime juice, and a spoonful of salsa. You will be in barbacoa heaven.