For the Chicken:

1. 1. Prepare the Chiles: Remove stems and seeds from guajillo chiles. Toast them lightly in a dry skillet over medium heat for about 2 minutes until fragrant.
2. 2. Blend the Sauce: In a blender, combine toasted chiles, garlic, onion (roughly chopped), cumin, salt, pepper, and 2 cups of chicken broth. Blend until smooth and set aside.
3. 3. Cook the Chicken: Place chicken thighs in a large pot or Dutch oven. Pour blended sauce over chicken along with an additional cup of broth. Bring to a boil over medium-high heat.
4. 4. Simmer Away: Reduce heat to low and cover. Let it simmer gently for about an hour or until chicken is fork-tender.
5. 5. Shred It Up: Remove chicken from pot and shred using two forks. Return shredded chicken to pot, stirring well to combine with sauce.

For the Tacos:

1. 6. Assemble Your Tacos: Warm tortillas on a skillet until pliable. Fill each tortilla with shredded chicken mixture and top with fresh cilantro and lime juice.