Clean, wash and pluck the salad into bite-sized pieces. Wash, halve and seed the grapes. Cut Leerdamer into cubes (ca.1 x 1 cm). Cut Roquefort into fine cubes.
Arrange the salad ingredients in a bowl. Wash orange hot, dab dry, grate peel thinly, squeeze juice. Mix juice, vinegar, salt and pepper, add oil and orange peel.
Pour the marinade over the salad.