Heat 1/2 inch of vegetable oil in a small skillet. When the oil is hot, slide in a corn tortilla. To prevent the tortilla from puffing and browning unevenly, press down on the center with tongs or a metal spoon. After about 20 seconds, flip it over to the other side and hold down the center again. When golden, remove from the skillet and drain on paper towels. Use three tortillas per tostada.
In a small saucepan, mix the black beans with just a bit of hot sauce to give a bit of a kick. Mash the beans slightly as you warm them over medium heat.
Get ready to assemble: Grab a crispy tortilla and set it on a baking sheet. Now layer beans, cheese, tortilla, beans, cheese, tortilla, beans and cheese.
Bake until the cheese melts. Pull it out and layer the top with a helping of the Braised Beef Brisket, lettuce, tomatoes, onions, cilantro, jalapenos, lime juice, avocado and sour cream.
Braised Beef Brisket:
Combine the beef consomme, soy sauce, lemon juice, liquid smoke and garlic in a large roasting pan (a disposable is just fine). Place the brisket in the marinade, fat-side up. Cover tightly with foil. Marinate in the refrigerator for 24 to 48 hours.
When ready to cook, preheat the oven to 300 degrees F.
Cook the brisket in the foil-covered pan until fork-tender, about 40 minutes per pound (6 to 7 hours). Transfer to a cutting board, slice against the grain and put the slices back into the cooking liquid. Serve immediately, spooning the juice over the slices.
You may store the pan in the fridge for up to 2 days, or freeze for use at a later date. If fat collects and hardens at the top, remove and discard.