Put the avocado and spring onions in a bowl. Season well and mix.
Heat the oil in a frypan over a low heat then stir in the zucchini and chilli. Cook for 1 minute, then stir in the prawns, lime zest, lime juice, Tabasco and 2 tablespoons water. Heat through for a minute, then spoon into the bowl with the chopped vegetables. Season well.
Cut the Iceberg lettuce in half then arrange some of the cups of lettuce on each plate, dividing them equally.
Spoon over the warm prawn mixture, then scatter with the chives and serve with the lime wedges.