Roast the garlic cloves in a dry skillet, turning them regularly, until they are blotchy black in spots and soft, 10 to 15 minutes. Or blanch them in a microwave in a small bowl covered with water at 100% for1 minute (poke a hole in each one to let the steam escape). When the garlic is cool enough to handle, peel (the soft cloves easily slip from the skins), roughly chop and drop it into a blender or food processor. Add the lime juice, oil, oregano, salt and pepper and blend everything into a marinade. Set aside 2 tablespoons of the marinade for the finished grilled steak.
Smear half of the remaining garlicky marinade on both sides of the steaks, lay them in a deep plate, and set them aside at room temperature (for quick penetration) while preparing the rest of the ingredients.
In a mixing bowl, use a potato masher or the back of a spoon to roughly mash the avocados, then drizzle in the remaining marinade. Taste and season with more salt if necessary. Cover with plastic wrap directly on the surface and refrigerate until serving time.
In a large (4-quart) saucepan over medium heat, cook the bacon or chorizo until it has rendered its fat and is beginning to brown. Add the beans and beer, water or broth. Let simmer while you grill the steaks. When the beans begin to simmer, turn the temperature to medium-low and cover the pan.
Light a fire in your grill and let it burn until you have a thick bed of coals that are quite hot and covered in white ash or turn your gas grill on to medium to medium-high. It’s best to have a very hot section of the grill for searing and a cooler section for letting the steaks finish cooking without burning. For indoor grilling, heat a grill pan (I like cast iron best) between medium and medium-high for about 10 minutes, to ensure it’s heated thoroughly. Turn on the oven to 250 degrees and set up a wire rack on a rimmed baking sheet.
Remove the steaks from the marinade, letting as much as possible drip back onto the plate. Lay them on the hottest part of the charcoal or gas grill or in the grill pan. After a minute or so, depending on the temperature and the cut of steak, use a pair of tongs to check if the steaks are ready to flip: All meat initially sticks to the grill (and know that some marinades are stickier than others) but will more-or-less release itself when it’s ready to flip. If you can’t easily lift the steaks off the grates, leave them a little while longer until they release themselves more. Then flip them (they should have rich-brown grill marks on one side) and cook the other side. To my taste, outside skirt is best served medium (they’re too chewy for me when rare)—that should take 7 to 10 minutes total, depending on the temperature of your grill pan or grill. If you want the steak medium rare, cook it about 2 minutes less. Skirt steaks are tasty at medium-well too, but, to ensure they stay juicy and don’t burn, you’ll want to move them to the cooler part of the grill or transfer grill-pan steaks to the rack and finish their cooking in the oven. All steaks are juiciest when you let them rest on a cooling rack set on a rimmed baking sheet and slide them into the very low oven or cover them with a loose tent of foil until you are ready to serve.
The beans should be the consistency of a thick bean soup. If they aren’t, stir in a little water, taste them for salt (unless you’ve purchased no-salt beans, they won’t need any). Finally stir in the chopped cilantro and pickled jalapeño.
Ladle the beans into bowls for each guest. Spoon a portion of guacamole onto each plate, along with a steak. Smear a little of the marinade you reserved over each steak. Warm tortillas, some salsa and a big salad are always welcome with carne asada.