This salad, with its blood orange vinaigrette, is sure to help beat the winter blues.
Cut ends off orange, then cut off peel, pith, and outer membrane following the curve of the fruit. Cut between each membrane to remove whole segments, and place in a small bowl. Squeeze juice from membranes into another bowl. (You should have about 2 tablespoons juice.) Discard membranes.
Cut each orange segment in half, and toss with escarole, celery stalks and leaves, and walnuts in a large bowl. Add reserved juice, oil, vinegar, salt, and pepper, and toss to coat. Serve immediately.