In a small receptacle, soak the bolillo in milk for 5 minutes. Grind well the onion and garlic in a mortar.
Add the tomatillos, mint, cumin, and grind together until it forms a paste. Add the mixture to the ground beef, salt and pepper, and mix well with your hands. Form Albondiga meatballs about 4 cm in diameter with a piece of the Chihuahua cheese inside. Set aside.
To make the sauce, blend the tomatoes, onion, garlic, chiles and water in a blender to a puree.
In a large pot, heat the oil and then add the puree. Let it boil around 8 minutes and then add the stock, bay leaf, and salt to taste Bring to a boil again. Reduce the flame and let it cook 5 minute. Add the Albondigas and cook on medium heat for 30 minutes. Spicy!