The pizza oven.
<br />
While in line, we were told by someone who's been coming here for two 
decades that the charring of the crust depends in part on how often they 
vacuum out the oven.  It happens multiple times each day. <br /> He also 
advised us not to order half-and-halfs, because it's not possible to get 
each half simultaneously cooked to the proper doneness of toppings.