1. Mix three tablespoons oil and shawarma spice together, then smear over fish, generously covering all surfaces. Marinate for 1/2 hour or up to one day ahead.
2. Heat a large frying pan with a thin layer of oil (about two tablespoons). Place the fish in the pan and cook for two to three minutes on each side or until just opaque. Set aside.
3. In a medium bowl, mix all salad ingredients. In a small bowl, whisk together all dressing ingredients.