06Peel the lukewarm potatoes, and cut them into 1/4-inch slices. Add them to the mussels along with the scallions and garlic. In a small bowl, mix together the salt, pepper, mustard, vinegar and oil, and add to the potatoes and mussels. Toss gently to mix.
07Arrange the salad greens on six plates, and spoon the salad onto the greens, dividing it evenly among the plates. Serve at room temperature.