In a large pot, combine the chicken thighs, chopped onion, minced garlic, chicken broth, apple cider vinegar, chili powder, cumin, oregano, smoked paprika, salt, black pepper, cinnamon, and cayenne pepper. Bring to a boil over medium-high heat.
Reduce the heat to low, cover, and simmer for about 30-40 minutes, or until the chicken is tender and easily shredded.
Remove the chicken from the pot and shred it using two forks. Return the shredded chicken to the pot and stir to combine with the broth and spices.
Heat a skillet over medium heat. Lightly toast each corn tortilla for about 30 seconds on each side until warm and pliable.
To assemble the tacos, place a generous amount of the chicken mixture onto each tortilla. Top with chopped cilantro and diced onion.
Serve with lime wedges on the side for squeezing over the tacos.