Put the raspberries, mustard and pomegranate juice into a food processor or blender and puree until smooth. With the motor running, add the olive oil in a slow steady stream, until a smooth emulsified dressing has formed. Season the dressing with salt and pepper, to taste. (If the dressing is too thick, add another tablespoon of juice.)
Place half of the dressing in the bottom of a large chilled salad bowl and top with mixed greens. Toss when ready to serve and garnish salad with additional raspberries.
Note: Leftover vinaigrette can be stored in an airtight container in the refrigerator for up to 5 days.