In a medium bowl, combine the Worcestershire, lime juice, soy sauce and chilli powder. Add the prawns and marinate 15 minutes.
Heat olive oil in a large frypan over medium heat. Cook the zucchini, onion and corn for 10 minutes or until the vegetables are tender. Cover to keep warm and set aside.
In a separate frypan heat olive oil over medium heat. Add the prawns and cook for 3 to 5 minutes, until the prawns are pink. Combine the prawns and the vegetables. Place prawns and vegetable mixture in tortillas; sprinkle with the cheese and coriander.