If they haven't changed anything Shephard's pie is the best attack food.
Shephard's pie is a level 40 recipe, Jerked beef is level 15. Both affect attack. Deviled Eggs gives the same amount of attack supposedly, but I don't think they give HP making pie the best. If these are too expensive on your server a cheap alternative is Meat Miq'abobs which you can even buy from the vendor in Ul'dah.
It is very hard to test damage currently on anything but Whiskerwall because of the extremely wide damage window (such as the test above mentioning a 20-30 damage difference with str/dex rings should just toss all those results in my opinion as they mean nothing in the context of how damage seems to be calculated unless the person testing did over 100 tests on a unique mob), however food does seem to have a significant difference.
My LS has had the best luck parsing Whiskerwall to get a better idea of what actually works, and that is because his high defense reduces the upper limit of the damage window giving more consistent results rather than the wild high's and low's you see on most things people are using to test which obviously are going to skew results.
You might be able to piece together some coherent study of exactly how damage is calculated if you had a great deal of stable data (meaning unique mobs, no change in gear within datasets, no change in direction of attack) comparing multiple builds, and then ran it through a proper ANOVA to get rid of the wild outliers and actually prove something. However, I don't have time to get a sample that size and I think most people aren't going to bother until 2.0 hits (if we are all still playing).
Until that time people are best off in my opinion testing on whiskerwall with small samples to get a broad idea of what works best. He is the current king of the mobs, and in my opinion he is all anyone looking at min/maxing should be focusing on. Most parsers allow you to narrow your parse to a single target, overall stats like total DPS and damage from the fight are great for showing off but show very little useful information for those looking to see where they can improve as individuals.