Clean, wash and pat dry salads. Pluck lollo rosso into bite-sized pieces. Roast walnut kernels in a coated pan without fat. Wash the grapes, dab dry and cut in half.
Cut the cheese into small triangles. Mix vinegar, mustard and orange juice. Season with salt. Gradually add the oil. Arrange salad, nuts, grapes and cheese together and sprinkle with the vinaigrette.
Serve immediately.