Place the anchos in a small saucepot and cover with the beef stock. Bring to a boil, then reduce the heat and simmer until very tender, about 10-15 minutes. Puree the mixture in a food processor or blender until smooth.
In a cast iron pot or Dutch oven, heat 2 tablespoons oil, a couple of turns of the pan, over medium-high heat. When the oil smokes, add the dry, cut bits of beef and brown well. Season with steak seasoning or salt and pepper; add the chorizo and render or brown for a couple of minutes more. Add the onion, garlic, bay leaf, cumin, coriander and oregano and cook for 4-5 minutes, or until the onion is softened. Add the tomato paste and stir for 1 minute, then add the beer and deglaze the pan. Add the ancho puree to the chili and stir in the beans. Simmer at a low bubble to thicken.
If serving as chili, serve in shallow bowls with suggested toppings, for garnish.
If making tostadas, while the chili is bubbling, place a small, high-sided skillet over medium heat with about 1 1/2 inches of oil. When the oil is shimmering, add one tortilla at a time and shallow fry on both sides until golden brown and crisp, about 1 minute per side. You may need to add some additional oil about halfway through. Place the tostadas on a paper towel-lined plate to soak up the excess grease.
To serve, place the tostada shells in shallow bowls and top with a large spoonful of the chili mixture. Top with your favorite suggested toppings, for garnish.