Preheat the oven to 425°F. Line 1–2 baking sheets with parchment paper.
If your chicken is not already seasoned, toss the 1 lb shredded chicken with the optional seasoning: chili powder, cumin, garlic powder, salt, and lime juice. Otherwise, proceed with your pre-seasoned chicken. (Method reference for shredding chicken: https://urbanmamaz.com/the-best-bbq-shredded-chicken-recipe/.)
Make the quick salsa (if using): In a small bowl, combine diced tomatoes, red onion, and minced garlic. Season with a pinch of salt and a little lime juice if desired. Set aside.
Arrange tortillas in a single layer on the prepared baking sheet. Brush or spray both sides lightly with olive oil.
Add a heaping tablespoon of shredded chicken onto one half of each tortilla. Top the chicken with a heaping tablespoon of shredded cheese.
Bake for 2 minutes until the cheese starts to melt and the tortillas soften. Fold each tortilla in half over the filling, gently press so they keep the shape, then bake for another 12–15 minutes, rotating the pan halfway through, until crisp and golden.
Transfer tacos to a platter. Spoon some of the diced tomatoes from the salsa and chopped cilantro over the top and serve with sour cream, guacamole, and the remaining salsa on the side. Enjoy!