This should be a rhetorical question...

[Estelyn Telcontar]

No, that would be Maiar who can choose their appearance, not Elves.

According to The Hobbit, the Wood-Elves were feasting at a fire, and Bilbo and the Dwarves found that

The smell of the roast meats was... enchanting...

Since the Elves did not welcome their unexpected guests, it is to be assumed that they planned to eat the meat themselves. The Wood-Elves also went hunting in the forest, we are told - and that word normally refers to animals, not vegetables!

The way Galion, the butler, is described, I could imagine that he would be well-rounded, since he loved drinking and feasting.

Now, we can quibble about The Hobbit not being quite canonical for Middle-earth as it is written in LotR. We could also debate whether the other Elves in Rivendell and Lothlorien might have had other eating habits than the Wood-Elves. And of course, it is possible that the Elves in the Undying Lands had changed their menus completely. At any rate, this is all the written evidence I could find concerning the diet of Elves in Middle-earth.

Perhaps HoME has more...