Vulcan Vegetarianism.
I've noticed that many fan-fic writers and role-playing games do assume that all Vulcans are Vegetarian, but I can't find out if it is a canonical fact or not. The 'Trek: The Encyclopaedia' says that they are, without giving any evidence, while the official 'Star Trek Encyclopaedia' doesn't mention it.
Tuvok
Presumably he ate Noss' sautéed spiders ('Gravity' VOY) as a survival measure. But if not, this is evidence that he is not a Vegetarian.
Tuvok once took part in the ritual of Tal'oth, in which he survived for four months in the Vulcan desert with only a ritual blade. ('Displaced' VOY). I'm assuming he used the blade to hunt for food, not just to cut open Cacti.
Spock
While both William Shatner and Leonard Nimoy are Vegetarians in real life, I find no evidence that Spock is.
Maybe that 'V' sign that Spock makes when he says "Live long and prosper" is actually a secret code for "Vegetarian."
The best evidence I can find is that, Spock, Tuvok and T'Pol, all eat the orange coloured plomeek soup, although Spock threw his away into the corridor. If T'Pol eats it, it must be Vegetarian, and it is a Traditional Vulcan dish, that reminds Tuvok of home.
Roddenberry's view
On the other hand, since it was GR's view, he may have had it in mind for Vulcans:
From 'Philosophy Sphere':
Interviewer: I remember the character of Commander Riker on the current series commenting on how it was no longer necessary for animals to be raised for food. [In the words of Will Riker, "We no longer enslave animals for food purposes."] Twenty-fourth century technology could create an analog of meat so that all the things associated with bringing meat to the table were no longer necessary.
Roddenberry: I look forward to that day coming. We would have our juicy T-bone steak without having to kill the animal. I feel different way about domestic animals now. I am a bit queasy about the way we raise our chickens and beef cattle and so on. It’s really ugly.
Interviewer: You’re talking about factory farms?
Roddenberry: Yes, it is just not a good thing. I also look forward to when we will contact other races and other life forms. What will our attitude be toward them? If we are not careful, we may see sentient life that is so different we won’t realize it is sentient. Because the creatures we meet don’t act and interact as we do, we might consider them valuable, much as many people disdain dolphins and whales today.