Roast the chiles over an open flame or under an electric broiler until they are blackened.  Wrap the chiles in a clean kitchen towel and then place in a paper bag for them to sweat, about 15 minutes. Remove the chiles from the bag and towel and scrape off the charred skin. Cut off the top and scrape out the seeds. Rinse the chiles to remove any excess skin or seeds. Dice the chiles and set aside.

Heat the vegetable oil in a medium sized sauté pan. Add the diced onion and sauté for until the onion becomes translucent. Stir in the dry corn tortilla mix until all of the vegetable oil is absorbed. Add the water and stir to combine well. When the mixture is thickened and bubbling, add the diced chiles. Season with salt and pepper. Cover and simmer for 10 minutes.

Meanwhile, heat your oven to 350°F (176°C).

To prepare the enchiladas, wrap the corn tortillas in a clean kitchen towel. Wet the bundle with a few spoonfuls of water and heat in the microwave for 1 minute so that the tortillas are steamed and pliable. (If you do not have a microwave, you can heat the tortillas individually on a griddle to make them pliable.)

Reserve half of your grated cheese for topping the enchiladas. Place ½ oz of grated cheese (14gr) on each tortilla and roll up. Place the rolled tortilla seam side down in an ovenproof ceramic casserole or a 9″x 13″ (23cm x 33cm) metal baking pan lined with parchment. Arrange the enchiladas in a single layer. You may opt to use two baking dishes.

Pour the prepared chile sauce over the rolled tortillas and then top with the remaining cheese. Cover the dish with aluminum foil. Place in the heated oven for 25 minutes until the cheese has melted.  Remove from the oven and spoon over the Mexican crema and garnish with chopped cilantro.