Starting at the top, with a very sharp knife, cut down into each avocado until you hit the pit. Cut completely around the avocado, top to bottom, touching the pit the entire time.
Pull the two halves of the avocado apart and remove the pit with a spoon.
Use the spoon to scoop the avocado out of the skin.
Slice 4 thin slices off one avocado. Reserve for garnishing the plate.
Dice remaining avocado.
Place avocado, celery, French dressing, tartar sauce, shrimp meat and crab meat in a large bowl. Mix gently but well.
Divide evenly into four mounds.
Form each mound into oval avocado shape.
Place on lettuce leaf-lined plate.
Top each mound with one of the reserved avocado slices.
Sprinkle with paprika for color.
Garnish side of mound with two cherry tomatoes and parsley sprig.
Serve with warm Italian bread.