Blend 850g of canned black beans with their liquid, 1 chipotle pepper in adobo, ½ cup of chopped onion, 3 garlic cloves, ¼ teaspoon of dried Mexican oregano, 1½ cups of vegetable stock, and 1½ teaspoons of kosher salt until smooth.
Heat 1 tablespoon of vegetable oil in a saucepan. Add the bean sauce and simmer for 5 minutes, stirring frequently. Add water if too thick to coat a tortilla.
Warm 12 corn tortillas in a skillet until soft and pliable; keep covered.
Dip each tortilla in the warm sauce. Divide 225g of crumbled queso fresco between them and fold in half. Spoon the remaining sauce over them and serve immediately.
