Heat olive oil in a large skillet over medium heat.
Add chopped onion and cook for 3-4 minutes until softened.
Add minced garlic and cook for 1 minute until fragrant.
Add chili powder, ground cumin, smoked paprika, dried oregano, salt, and black pepper to the skillet. Stir to combine and cook for 1 minute to toast the spices.
Place chicken breasts in the skillet and pour chicken broth over them.
Cover the skillet and simmer on low heat for 25-30 minutes, or until the chicken is cooked through and tender.
Remove the chicken from the skillet and shred it using two forks.
Return shredded chicken to the skillet and stir to coat with the remaining sauce. Cook for 2-3 minutes to absorb flavors.
Allow the chicken to cool, then transfer to an airtight container and refrigerate if making ahead.
When ready to serve, warm the corn tortillas in a dry skillet or microwave.
Assemble tacos by placing shredded chicken on each tortilla, then topping with shredded cheddar cheese, shredded lettuce, diced tomato, a dollop of sour cream, and chopped cilantro.