I am a vegetarian and my girlfriend is vegan, so a lot of the time I eat vegan. On a 2 day tour we baked some potatos at home then reheated them on the fire at night, along with corn and other things. That only works for short trips.

You can always look for "accidentally vegan" foods, you can find dozens of list and items online; here is one I found. (HERE)

I eat lots of peanut butter based items, and pasta. I make my own treats for rides, And you can find "vegan" jerky more, if you want to be "one of the boys".

Advice from my girlfriend:
You could also use the boxed 5 minutes rice, and just boil water for it, as well as using canned beans.
Vegan food is pretty easy to get a hold of, even Wal-marts carry non-dairy milks (as well as Krogers, and some gas stations).
Cans of soup are easy to reheat over a fire.
Making granola bars is a good plan. Carrying nuts and dried fruits is as well.
Primal Strips make delicious vegan jerky.
There are so many options out there for vegan/vegetarian cyclists on their travels!