Marinate the chicken. In a bowl, whisk 2 tbsp oil, orange juice, lime juice, chili powder, paprika, garlic powder, cumin, oregano, salt, and pepper. Toss chicken to coat and let sit for 15 to 30 minutes.
Sear the meat. Heat 1 tbsp oil in a large skillet over medium-high heat. Add chicken in a single layer. Cook 5 to 6 minutes until dark crust forms, flip, and cook 4 to 5 minutes more until done.
Chop and rest. Remove chicken to a cutting board, let rest 3 minutes, then chop into bite-sized pieces.
Warm tortillas. Briefly heat corn tortillas directly in the hot skillet with the leftover chicken juices until pliable.
Assemble. Stack two tortillas, fill with chopped chicken, and top with diced onion and cilantro. Serve with lime wedges.