In a large bowl add the corn husk and submerge in room temperature water and let soak while you make the filling.
In a large skillet with high sides add 1 tbsp of oil and heat on medium-high heat. When the oil is hot add in the chile rellenos, tomatoes, serranos, onions and salt to taste. Cover with a lid and let it cook for about 5-7 minutes stirring occasionally to prevent burning on the bottom.
Once the veggies have cooked down add in the garlic and cook for about 1 min. Add your shredded chicken in and stir to combine and let cook for about 3-5 minutes. You want to cook out as much liquid as you can. When done, set aside and allow to cool before assembling the tamales.
Grab one of the corn husks out of the water and spread about 2 spoonfuls of masa on your corn husk. If your masa is too thick and difficult to spread add a few tablespoons of chicken stock to your masa and mix well. You want to spread your masa evenly and not too thick or thin.
Add a spoonful of filling on top of the masa. You don't want to skimp on this part but don’t over load it either!
Fold each flap in and then fold the bottom in. Pictures shown below.
Repeat until you run out of masa and filing. Should make between 30-40 tamales depending on the size you make them.
In a large pot with a steamer insert add water making sure it does not touch the steamer basket. Arrange your tamales so that the open side is facing up. Cover the tamales with aluminum foil and cover with a lid. Steam the tamales for 1 hour and 30 minutes to 2 hours. You’ll be able to see if they’re done if the masa is fully cooked and doesn’t look raw/slimy.
Turn off the heat when done and let them sit for at least 30 minutes. Enjoy!!