Place the dried Rancho Gordo Midnight Black Beans into a large bowl and wash well, removing any beans that are broken or any other debris. Transfer the beans to a large container and cover with cold water by 4 – 5 inches. Let the beans sit for at least 8 hours or overnight to re-hydrate.
Pour off the soaking water and re-rinse the beans. Place them into a large Dutch oven or pot with a lid and add the garlic cloves, chipotle peppers, oregano, epazote and Aecht Schlenkerla Rauchbier Märzen. Top the liquid off with either vegetable stock or water until the beans are fully covered. Place the pot over medium heat and let the beans simmer gently for about an hour, or just until the beans are cooked through. If the liquid drops to below the beans, add more stock | water.
Strain the beans through a colander, with a bowl underneath to catch and save the liquid. In a clean pot or large skillet over medium-high heat, add the fat, using olive oil or rendered pork fat, bacon fat or duck fat. Once the fat has melted, add the cooked beans and toss to coat in the oil. Using a potato masher or large spoon, mash the beans to a paste, seasoning with salt to taste. Add some of the reserved bean liquor if the mixture starts to look too dry. The finished consistency should be that of rustic mashed potatoes.
Any leftover beans can be used in burritos or tacos, spread over nachos, added to a seven-layer bean dip or to any other recipe that calls for refried beans.