Before I start this rant, I just want to say that I have no ill feelings towards vegans or veganism. It is not for me but I can see the benefits and why people would want to do it. However, when it comes to the Ching Hai cult, veganism is being used as a weapon in a completely unhealthy way.
Ching Hai is always talking about veganism. Everything relates back to you have to be a vegan or else you are evil when it comes to this woman. A large part of the reason behind this is because the master herself owns a food processing company and the Loving Hut franchises. The other part is that veganism is a way for her to control her followers.
Having control over something so vital and personal is a sure sign of a cult. When you can control every aspect of someone's personal life, you control that person completely.
Buddhism doesn't even require you to be a vegan.