Shelby Duffy

Step 1

In the work bowl of a food processor, pulse prawns until finely chopped.

Step 2

In a medium bowl, stir together mayonnaise, lemon juice, salt, and pepper until combined. Stir in watercress and prawns. Transfer prawn salad to a covered container and refrigerate for several hours until cold, up to a day.

Step 3

Divide prawn salad among 3 bread slices and spread in a thick, even layer. Top each with a remaining bread slice to make 3 whole sandwiches.

Step 4

Using a serrated bread knife in a gentle sawing motion, trim and discard crusts from sandwiches to make even squares. Cut each sandwich diagonally into 4 equal triangles. Serve immediately, or cover with damp paper towels, place in a covered container, and refrigerate for up to 2 hours until serving time.