- For dressing, combine yogurt, orange juice, zest, honey, and vinegar in a small bowl. Whisk in oil. Season to taste with salt and freshly ground black pepper; set aside.
- Cut broccoli into small florets, trimming off and discarding woody parts of stalks. Using a vegetable peeler, peel the outer ⅛ inch from each stalk. Cut stalks in half lengthwise, then into bite-size pieces. You should have about 9 cups broccoli.
- Fill a large stockpot with about 2 inches of water and add salt. Bring to a simmer. Add broccoli, replace lid, and steam for about 6 minutes, tossing once, or until broccoli is crisp-tender.
- While broccoli is cooking, prepare a large bowl of ice water. Using tongs, plunge cooked broccoli into ice water to cool. Drain and set aside.
- Transfer broccoli to a large mixing bowl. Add celery and cranberries and toss with enough dressing to coat. Sprinkle with walnuts. Serve immediately or refrigerate until ready to eat.