Begin by heating the olive oil in a skillet over medium heat.
Add the shredded chicken to the skillet along with chili powder, cumin, smoked paprika, garlic powder, salt, and pepper. Stir well to combine and cook for about 5-7 minutes, until the chicken is heated through and coated with spices.
While the chicken cooks, warm the corn tortillas on a separate dry skillet over medium heat for about 30 seconds each side until they are pliable.
Assemble the tacos by placing a generous spoonful of the spiced chicken onto each tortilla.
Top the chicken with red cabbage, chopped cilantro, diced tomatoes, and avocado.
Drizzle the tacos with lime juice and sprinkle with crumbled feta cheese if using.
Serve immediately, garnished with extra cilantro and lime wedges on the side.