When tacos vampiros are cooking on the grill, the corn tortilla edges fold up. This is supposedly the origin of the name, because the edges look like bat wings. It's sort of a cross between a tostada and a taco.
Light your grill. Toss the beans or seitan strips with the oil and salt and transfer to a well-oiled grill pan. Place the grill pan on the grill and slowly stir while they grill until blackened. This should only take a few minutes. Remove from the grill and set aside.
Place the tortillas on the grill. When the edges start to curl from the heat, sprinkle the cheese on the tortillas, leaving a rim around the edge. When the tortillas are hard and crunchy, remove them from the grill. Top the tortillas with the beans or seitan strips, followed by the onion, cilantro, salsa, and guacamole.
Make In The Oven: Dress your beans or seitan the same way, but place them in a baking dish and leave them uncovered. Roast them at 400°F for 15 minutes, opening the oven to stir them every 5 minutes. While they are baking, place your tortillas in the oven on the lower rack. When they begin to curl, slide the lower rack out, dress them with the cheese, and return them to the oven. Once the cheese melts, remove them from the oven and set them aside. Dress them just as you would above.