For the adobo sauce: Remove the seeds and stems from the peppers and then toast them in a cast iron skillet on high heat for a few minutes, until you can smell their aroma.
In a three quart sauce pan boil the peppers along with two cups of water, for five minutes. Drain the peppers, and then put them in the blender along with two cups of fresh water, the vinegar, oregano, cumin, cinnamon, and cloves. Blend until the mixture is smooth.
Preheat the oven to 300 degrees.
For the Birra beef taco filling: Dry off the short ribs and sprinkle them with the salt, pepper, and garlic powder. Heat the olive oil in a Dutch oven on medium heat. Sear the ribs, a few at a time, on all sides. When they're al browned add them all back to the pot along with half the adobo sauce (you can freeze the rest for another use), the chicken stock, the bay leaves and the thyme. Cover the pot and bake them for three hours, or until they're very tender.
Remove the meat from pot and shred it. Pour the liquid in the pot into a measuring cup. The fat will rise to top. Remove and discard the fat. Pour the liquid back into the pot. At this point you could dip the tortillas into the liquid, fill them with meat, and then brown them in a cast iron skillet in a little butter. But, I prefer to add the meat back to the pot and stir the liquid in . Then, I fill the tacos with the meat and the following salad.
For the salad: toss together all the vegetables and the lemon juice and extra virgin olive oil. Season with some salt and pepper. I think the salad really cuts a lot of the richness of the meat and adobo, and I highly recommend it.