Place 4 dinner plates in the refrigerator to chill. To make the dressing, place the first 7 ingredients in a small bowl or jar with a tightly sealing lid. Whisk or shake to combine. Refrigerate until needed.
Place the wine in a small pot and bring to a boil. Add the mussels, cover and cook just until they open, about 1 to 2 minutes. Transfer the mussels to a plate, cool to room temperature and refrigerate at least 1 hour.
Make a bed of the salad greens on each chilled plate. Artfully arrange the mussels, prawns, smoked salmon, tomatoes, cucumber and red onion of top of the greens. Stir or shake the salad dressing and then drizzle some over each salad. Garnish each salad with a lemon wedge and serve.