Slice potatoes in half, place them in a large saucepan and cover with water. Bring to a boil. Reduce heat and cook for an additional 10-15 minutes until fork tender. Drain well.
Meanwhile, in a large bowl, whisk together the mayonnaise, sour cream, chicken broth, dijon mustard, celery seed, salt and pepper.
Add cooked potatoes to mayonnaise mixture and stir well.
Then add ham and stir again.
Finally, gently stir in cheese, tomato and green onions.
Cover bowl with plastic wrap and place into the refrigerator for at least 2 hours.