Before they exploded around the United States food truck market a few years ago, they are full of slowly stewed meat usually goat or with a deeply built, chili-based spicy stew at the core, both for frying those tacos (in the skimmed fat) and depreciating them (in the braising liquid).
The beef birria tacos were initially used as a stew with Spanish goats in the 1500s, but they were gradually refined to make their gamey goats more comfortable. In 1980, another taquero was added, putting a vital component of the dish on the line. Today, I'll add a standard beef birria and quesabirria tacos with a "consomme" on the side for dipping.
This takes a lot of time before we dive in. It's possible that you're slow-stewing/braising large cuts of meat into delicious, soft foods that you can bite through. That's not a straightforward process. Yes, in the knowledge that a lot of people don't live in a city where taco trucks are the norm, so making them at home is a process of keeping them going. No, in the sense that this process requires forever. It's a lot of work for
All of that, this is really freaking delight. So, make an informed decision whether or not you wish to give these shots. I promise you that the end is just right.