Place flour on a plate and season. Dust chicken in seasoned flour. Shake off excess. Reserve any remaining flour.
Heat half the oil in a large flameproof casserole dish or large deep frying pan over high heat until hot.
Cook the chicken, in two batches, for 2-3 minutes on each side, or until browned. Remove to a plate.
Reduce heat to medium. Add remaining oil and onion to same dish. Cook, stirring occasionally, for 5 minutes, or until soft. Add mushrooms, Fajita seasoning and reserved flour.
Cook, stirring for 1 minute.
Return chicken to pan with salsa and stock. Bring to boil. Reduce heat. Cover and simmer gently for 25 minutes, or until chicken is just cooked. Remove lid.
Simmer for a further 5 minutes, or until sauce is thickened slightly. Sprinkle over coriander and jalapeno. Serve with lime wedges and warm tortillas.
