In small bowl, whisk together pineapple juice, onion, mustard, lime juice, mint, salt and pepper.
Place shrimp in another bowl; add 1/4 cup of the marinade and toss to coat shrimp.
Cover and refrigerate for 1 hour.
Reserve remaining marinade.
To serve, place bed of greens on each of 4 plates.
Arrange pineapple, honeydew melon and cucumber on top of greens.
Top with shrimp and drizzle salads with remaining marinade.
Serve immediately.
Makes 4 servings.
