For dressing, in small bowl, whisk together yogurt, lemon juice, honey, cumin, orange zest, and sea salt. Cover and refrigerate for flavors to meld.
While dressing rests, in medium bowl, gently mix walnuts, celery, apple, cranberries, oranges, and mint. Be sure not to squish the orange segments as the extra juice will make the dressing runny.
Remove dressing from refrigerator and gently fold into salad mixture. Fill endive leaves and arrange on platter. Serve immediately.