In a large skillet, heat 1 tablespoon of oil over medium heat. Add diced onion and cook until soft and golden, about 5 minutes. Stir in minced garlic, chopped chipotle pepper, and spices. Cook for 1-2 minutes until fragrant, then mix in tomato paste.

Add the drained black beans and vegetable stock to the skillet. Lightly mash beans while stirring, simmer for 5 minutes and mix in fresh lime juice before removing from heat.

Wrap corn tortillas in a damp paper towel and microwave for 30 seconds to make them warm and pliable.

On a greased baking sheet, lay each tortilla flat, fill half with the black bean mixture, and sprinkle cheese on top. Fold over to form tacos.

Preheat oven to 400°F (204°C) and bake tacos for 20-25 minutes, flipping halfway until golden brown.

Remove tacos from oven, let cool for a few minutes before serving with toppings like avocado, salsa, or fresh cilantro.