1. To make the beans, drain the beans, reserving some of the liquid from the can. Rinse the beans. Heat the lard in a frying pan over medium heat. Add the onion and garlic and cook about 7 minutes, until the onion is golden. Increase the heat to medium high. In batches, add the beans and stir and mash them with a wooden spoon, adding some of the bean liquid, as needed, to make a coarse puree. Add the stock cube and reduce the heat to low. Cook, stirring often, until thick

2. To make the sauce, combine the chiles and boiling water in a small bowl and soak for 15 minutes. Drain, discarding the liquid. Purèe the tomatoes, chiles, onion, and garlic in a blender. Heat the oil in a large frying pan over medium heat. Add the tomato mixture and cook, stirring frequently, about 5 minutes. Add the vinegar, tomato paste, cumin, oregano, and sugar and simmer over medium-low heat for 10 minutes.

3. To assemble, heat 4 tbsp of the oil in a frying pan over high heat until shimmering. Fry each tortilla for approximately 30 seconds on each side, until hot but not crisp. Transfer to paper towels. Add the remaining 2 tbsp oil to the pan. Add the eggs and fry according to your taste.

4. To serve, place each tortilla on a dinner plate and top with an egg. Spoon some of the tomato sauce over each, and garnish with the avocado slices and cilantro. Add a spoonful of the beans to each tortilla, and serve hot.