In a large pot, combine the chicken thighs, quartered onion, minced garlic, dried chile peppers, and water. Bring to a boil, then reduce to a simmer. Cook until the chicken is tender, about 30 minutes. Remove the chicken and let it cool slightly before shredding.
In a mixing bowl, combine the shredded chicken, green chiles, thawed corn, garlic powder, salt, and chile powder. Mix until well combined and set aside.
In another large bowl, combine the Maseca masa with 2 1/2 cups of beef broth and mix until a dough forms. The masa should be soft and pliable. If it's too dry, add a little more broth.
Soak the dried corn husks in warm water for about 30 minutes until they are pliable. This will make them easier to work with when wrapping your tamales.
Take a soaked corn husk and spread about 1/4 cup of masa onto the husk, leaving a border at the edges. Add a tablespoon of the chicken filling in the center. Fold the sides of the husk in and roll it up tightly. Place the tamale seam side down in the steamer basket. Repeat with the remaining husks, masa, and filling.
Fill a large pot with water, placing a steamer basket inside. Bring the water to a boil, then reduce to a simmer. Arrange the tamales in the basket, standing up with the open ends facing up. Cover the pot with a lid and steam for about 1 to 1.5 hours, or until the masa easily separates from the husk.
Once cooked, let the tamales cool for a few minutes before serving. Enjoy them with your favorite salsa, guacamole, or sour cream.
