Start by heating a large skillet on medium-high heat. Once heated, add in the oil, and let it come to temperature for about 10 seconds. Add the pork, and sear the pork on each side. Once seared, place the pork into your slow cooker. Return the skillet to the stove, and toss in the chopped onion. Cook for about 2 minutes, then add in the water to deglaze the skillet. Pour everything into the slow cooker.
With the remaining ingredients, with the exception of the tortillas, cilantro, and hot sauce, add to the slow cooker, and give everything a cook stir. Cover, and cook on low heat for 7 hours.
Before serving, I like to lightly shred the pork, however leaving some cubes together. Now you can go ahead and serve as is, but I like to sear mine on the stove once again. So what I do is add a skillet on medium-high heat to the stove. Next I add in however much carne guisada I think will hold with two tacos, and mixing it around for a couple of minutes until some of the pork caramelizes, and some of the juices run clear.
Add to the warmed tortillas, and dig in.