To prepare dressing: Combine mayonnaise, yogurt, sour cream, vinegar, mustard, honey, onion (or chives), tarragon (or dill) and onion salt (and/or celery salt) in a bowl until well blended. Season with white pepper. Taste and adjust seasonings, if desired.
To prepare salad: Combine pasta, broccoli, ham, bell pepper, diced onion and raisins in a large bowl. Add dressing and toss until evenly incorporated. Cover and refrigerate to blend the flavors for at least 30 minutes and up to 2 days.
Serve on a bed of spinach and radicchio, garnished with slices of red onion.