Mix spices, garlic, Tabasco, lemon juice and 2 teaspoons oil in a large shallow dish. Add chicken and rub all over with spice mix. Cover and refrigerate 10 minutes.
Heat a large non-stick frying pan over a medium heat. Add chicken and cook for about 2-3 minutes on each side, or until browned and cooked through. Remove, cover with foil to keep warm.
Heat remaining 2 teaspoons oil in same frying pan. Add onion and capsicum. Cook, stirring, for 4-5 minutes or until lightly browned and just tender.
Heat tortillas as directed on packet.
Thickly slice chicken. Place tortillas on a serving board, top with onion, capsicum and chicken. Add lettuce, avocado, cheese and yoghurt. Fold in half to serve.