For the casserole: Preheat the oven to 375 degrees F.
Bring the beef stock to a simmer in a pot; add the ancho chiles and just enough water to cover and cook to reconstitute them. When softened, transfer to a food processor and puree.
Char the poblanos evenly over a flame or under the broiler. Cool in a covered bowl, and then peel, seed, chop and reserve.
Arrange the tortilla strips on baking sheets, spray with cooking spray and season with salt. Bake to deeply golden brown, 10 to 15 minutes.
Heat the oil, 2 turns of the pan, in a large, deep skillet over medium-high heat. Add the chorizo and brown, crumbling the meat. Add the beef and continue to brown and crumble the meat. Add in the beans, coriander, cumin, garlic, onions, poblanos and ancho puree and cook together a few minutes to combine the flavors.
Layer half of the tortilla strips in a casserole dish and top with the chorizo and beef mixture. Cool and store for a make-ahead meal (store the remaining tortilla strips in a foil pouch until using), or bake to serve. To bake, top the room-temperature casserole with the remaining tortilla strips and the cheese and bake at 375 degrees F until bubbly and hot through, 40 to 45 minutes.
For the avocado cream: Whiz up the sour cream, avocado and lime juice in a food processor.
Top the casserole with the pickled jalapenos, lettuce, tomatoes and onions and dollop the avocado cream over top (or pass at table).