Most people i've talked to have not figured this out yet, and I didn't see any posts about it, so here it goes:
If you got into a major city of the opposite faction and right click on their Bonfire (holiday one) then you get Flames of (Name of City). You turn these in to the Loremaster in one of your factions major cities, or Shattrath for 10g and well fed food. These holiday well fed foods stack with normal well fed. On my rogue I was able to have the holiday +20 hit rating and the Spicy Talbuk for another +20 hit rating. I did the same thing on my priest with +healing food, and + defence on my warrior. They all stack!