In a medium skillet, heat 1 tablespoon of cooking oil over medium heat. Add 1 diced onion and sauté for about 5 minutes until golden and softened. Stir in 2 minced garlic cloves, 1 chopped chipotle pepper in adobo, 1 teaspoon each of cumin and chili powder, and 2 tablespoons of tomato paste. Cook for another 2 minutes until fragrant, stirring occasionally to prevent sticking.

Add 1 can of rinsed black beans to the skillet, along with 1/4 cup of vegetable stock. Gently mash the beans with a fork to create a creamy texture, while leaving some whole for heartiness. Let the mixture simmer on low heat for about 5-7 minutes until thickened, then remove from heat and squeeze in lime juice.

To make the corn tortillas pliable, wrap them in a damp paper towel and microwave for 30-40 seconds. Keep the tortillas warm by covering them with a kitchen towel until ready to use.

Preheat your oven to 400°F (200°C) and coat a baking sheet with cooking oil. Place the warmed corn tortillas on the sheet, and spoon a generous amount of the black bean filling onto each tortilla. Sprinkle cheese on top, fold the tortillas gently, and ensure they are sealed.

Bake the assembled tacos for about 15-20 minutes, flipping them halfway through. They should be golden brown and crispy when done.

Allow the Crispy Black Bean Tacos to cool for a couple of minutes before serving. Serve with your favorite toppings like avocado, salsa, or cilantro.