1. For the sauce: Blend the black beans with the chopped onion, garlic clove, sliced jalapeños, chicken stock, and sour cream until smooth. Season with salt and pepper to taste and bring to a boil.

2. For the filling: Heat the 2 tbsp of oil and sauté the sliced onion until translucent, add the sliced jalapeños, season with salt and pepper to taste.

3. To assemble: Heat the ½ cup of vegetable oil and fry each tortilla briefly on both sides. Spoon some of the filling on each tortilla and roll. Pour the bean sauce over the chicken tacos, sprinkle with cheese and finish with more sliced jalapeños to taste.