To make the beans, heat the oil in a large skillet. Add the onion and cook until softened, stirring occasionally, about 4 minutes. Add the garlic and cook for 1 minute. Add the black beans, cumin, chili powder, paprika, and oregano. Stir to coat the beans in the seasonings.
Add the vegetable broth (or water), tomato paste, lime juice, salt, and pepper. Stir to combine and cook for about 3 minutes, or until tomato paste dissolves and the beans thicken. Taste and season with additional salt and pepper, if necessary. You can mash them a little with a large spoon if you want.
To make the crispy tortillas: Add the oil to a small skillet until it is 1/2 inch up the sides. Heat the oil over medium-high heat until hot (350 degrees), this will take about 5 to 7 minutes. Line a plate with paper towels and place by the skillet.
When the oil is hot, carefully place a tortilla in the hot oil and cook until it is blistering but still soft, about 10 to 15 seconds. Using tongs, turn tortilla over and then immediately fold to form a taco shell. Once the tortilla is holding its shape, turn until crisp and golden all over, 15 to 30 seconds longer.
Transfer to the prepared plate and sprinkle with cotija cheese and a little salt on the inside and outside of the taco shell. Make sure you sprinkle the cheese on when the tortillas are hot so it will stick. Continue frying the tortillas. If the oil starts to smoke, it is too hot, turn down the temperature and wait a bit.
To assemble the tacos: Spoon the black beans into the center of the crispy tortillas. Top with the creamy avocado sauce, cheese, shredded cabbage, pickled red onions, pico de gallo, cilantro, and a little cotija cheese (or whatever toppings you like). Serve immediately.