What to charge for consultation, i am a vegan ...

Pro rate your time. What is it worth per hour?

I'd suggest you calculate your 'hourly' rate and then advise people that you charge per consultation, at a rate of 'X' per set amount of time.

You may wish to set a minimum time as an automatic charge (i.e., 15 minutes) so that no matter how little time the person uses, you'll still get paid.

I think you know how much you are worth. The thing is you are not that sure if it is right or not. But let me tell you this, price yourself as if you are the one who wants the consultation badly.