Peel and wash potatoes; cook in boiling water until just fork tender (do not over cook).
Cool and dice approximately 1/2 x 1/2-inch; combine with all other diced items (onions, pickles, pepperoni, cheeses, celery and black olives). Fold all of these ingredients gently with 1/2 cup of mayonnaise until mixed.
Refrigerate for at least a couple of hours, overnight is even better (this is important).
Add all spices and the rest of mayonnaise and minced garlic; gently fold until mixed. Refrigerate 30 minutes to 1 hour before serving.