You will need a 5qt pot or something of similar size. Place in stove and add the bacon previously cut in small pieces, turn the fire to medium-low and cook, stirring often, until most of the fat is rendered and the bacon has browned and looks crispy.
Remove the bacon from the pot using a slotted spoon, leaving the fat behind and set aside for later. Add the diced potatoes, salt and fry on medium-high heat until crispy, stirring often.
Remove the potatoes from the pot using the same slotted spoon, leaving the fat behind and set them aside for later. Add the diced white onion, and sauté on medium-low heat stirring constantly until translucent.
Add the meat and stir to blend all together, increase the heat to medium-high, and let cook until meat starts rendering both fat and water. Continue to cook until all this water cooks off and the rendered fat looks like it glazed the meat. Stir often.
While the meat cooks, make the sauce. To the cup of a blender, add the quartered tomatoes, halved serrano chile, garlic cloves, cumin, oregano, chicken bouillon, and the reconstituted Ancho chile (DO NOT add the chile water, it’s very bitter; discard that water). Add 1 cup of tap water (omit this if you’re using chicken stock), for everything to blend, and liquefy into a uniform red sauce.
When the meat looks like it’s glazed, and the onions are starting to stick to the bottom, stir everything once more being sure to scrape the bottom to make sure nothing is stuck, add the bacon and the potatoes, and add the sauce. Rinse the cup with a bit of water and add it also to the pot, so no sauce is left behind in the blender cup.
Stir well to make sure everything is incorporated. Add the cilantro bunch on top. Reduce fire to low, and simmer until the whole thing thickens. It will take about 20-30 minutes; however, the longer you cook it for at a low fire, the better it will be. To do that, you will need to add water as it dries out to avoid it sticking and drying out into a horrible tough mess.
When it acquires your desired thickness and consistency, kill the fire and add the juice of one lime. Make some tacos! It really won’t need anything extra on top, but sliced avocado always goes well with it. Traditionally it’s served on Flour Tortillas, but corn tortillas work just as well! Enjoy!