Is this a run-on sentence?
If you have a hankering for a delicious bowl of soup, you should try Mr. Montoya's smoked French onion soup made with Vidalia onions, smoked Gruyère cheese, and fresh thyme.

 - no
 - yes
This is not a run-on sentence. It is not formed from two sentences that have been run together without appropriate punctuation.
If you have a hankering for a delicious bowl of soup, you should try Mr. Montoya's smoked French onion soup made with Vidalia onions, smoked Gruyère cheese, and fresh thyme.