You admitted that the attitude about the subject was the annoying part. Not so much the dietary choice. Maybe try being empathetic and calmly think about what the motives are before reacting. Many people use diet to control something in their lives. Most of her life is being controlled by a cult so having something so "different" from the herd might make her feel special and extra "good". Like a real individual. Maybe trying to understand this will help with your ultimate goal of not being so annoyed by it. Make it easier to brush it off so to speak.
I went Vegan once for a month before I was dying for some goat cheese :) yum. I remained vegetarian for about 10 months after that. I'll admit that I was having a rough time in my personal life (my husband was constantly threatening suicide and threatening me that I better not tell anyone). I became totally annoying and preachy about my reasons for doing it. It was just something other than the painful events in my life to focus on.
Also, The Borg is really hard on people to be "perfect". It can make some push themselves to obscenely high standards for themselves and those around them. I relate to this too. If you think God is going to Kill you for not attending all the meetings, notstudying properly, not putting in enough hours in service or not serving where the need is greater if you have the ability, or for going to a 4 year college etc etc etc, why wouldnt he kill you for not taking the environment into consideration? (it take a lot of fossil fuels to raise meat). He did say he would put to ruin those ruining the earth didnt he? get my drift? Feel sorry for her. She's probably dying inside trying to be perfect.
Though I still try to make healthy earth conscious choices at the market, I have become much more balanced in general since those traumatic times have cooled.
I hope this might give you a new perspective.
p.s. VEgan-"Do you know what they do to those chickens?!" Jim Gaffigan-"no, but it's Delicious!"
FMW
