Shell the prawns reserving 2 of them for the decoration. Cut the rest of the prawns in 1 to 2 cm pieces.
Slice the tomato. Take ½ an avocado and finely slice it length way. Shred 2 of the Lettuce leaves.
Prepare the Cocktail sauce. In a bowl, mix the mayonnaise with the Tomato sauce, the Worcestershire sauce and a few drops of Tabasco. Add salt and pepper to taste and mix thoroughly. The sauce should have a thick and creamy consistency.
Add the Prawns to the cocktail sauce. Mix until all of the Prawns have a light covering of sauce.
Next, lay one whole salad leaf in the base of the Martini glass. Add the shredded salad, the avocado and the tomato slices; arrange them so as to create a well in the centre. Add half of the prawns. Repeat the same step for the other glass.
Just before serving, add a Prawn and a slice of lemon in each glass. To finish, sprinkle the Prawns with a little chopped parsley.