For the tortillas: Preheat the oven to 190°C. Lay the tortillas on a baking sheet, brush both sides with the oil and sprinkle with salt. Bake until golden brown and crispy, about 10 minutes.
For the cube steak: Toss the steak strips with 1/2 teaspoon salt and 1/4 teaspoon pepper. Heat 2 tablespoons of the oil in a large skillet over high heat until lightly smoking. Add half of the strips and cook, tossing until the strips are browned on all sides, but not completely cooked through, 1 to 2 minutes. Remove with a slotted spoon to a large bowl and repeat with the other half.
Remove all but 1 tablespoon of oil from the skillet and reduce the heat to medium-high. Add the onions and 1/2 teaspoon salt. Cook, stirring frequently, until golden brown, 6 to 8 minutes. Add the garlic and 1/4 teaspoons of the oregano and cook for 1 minute. Add the broth and stir with a wooden spoon to loosen any browned bits. Add the steak strips and any accumulated juice and simmer until thickened slightly, about 4 minutes. Remove from the heat and add the remaining 1/4 teaspoon oregano, lime zest and lime juice and mix well.
For the beans: Heat the oil in a medium skillet over medium-high heat and add the chili powder. Cook until fragrant, about 15 seconds. Add the black beans and toss to combine. Add the broth, 1/2 teaspoon salt and 1/4 teaspoon pepper and bring to boil. Using a masher, smash the black beans, stirring occasionally to incorporate into the broth, until thick. Remove from the heat.
For the chili-lime mango: Toss the mangoes with the lime zest, lime juice, chili powder and 1/8 teaspoon salt.
To assemble the chalupas, spread a thin layer of smashed black beans on each crispy corn tortilla and divide the steak among them. Top with some chili-lime mangoes and serve with lime wedges and pickled jalapenos.