In a large bowl combine the mayonnaise, tomato puree, Worcestershire sauce, lemon juice and 1 tbsp of chives and Tabasco sauce. Season with salt and pepper.
Place the lettuce into the base of the serving glass/bowl. Add some cucumber and watermelon, then add a spoonful of the sauce. Top with some prawns, and then add another spoonful of sauce. Sprinkle with the remaining watermelon, cucumber, and chives and add a wedge of lemon.