To make the dressing, put the olive oil, vinegar, mustard and orange zest in a small bowl and
mix well. Season with salt and freshly ground black pepper, to taste.
Preheat a barbecue or griddle pan to medium heat. Lightly brush the prawns with a little of the
dressing, arrange on the grill plate or pan and cook for 5 minutes, or until crisp and opaque.
Transfer to a large bowl.
Finely slice the onion lengthways and add to the bowl. Slice the avocados into large wedges and
add to the bowl. Slice the cheeks off the mangoes and peel them. Cut into slices and add to the
Discard the damaged outer leaves of the lettuces and tear the leaves into smaller pieces. Add to
the bowl. Pour in the dressing and toss lightly before serving.