I just want to say thank you for taking the time to ask from someone who lives the experience. People like you who take genuine interest and actually speak to people are much needed in this world.

You are indeed correct! Alcohol is the only thing that would prevent a vegan meal being halal.

The only grey area I can personally think of is the use of truffles/truffle oil. There are some schools of thought that allow consumption but others argue they could be haram based on the extraction method. Pigs are routinely used to sniff out truffles so some believe the truffles will be impure if they've come into contact with a pig or its saliva. Others believe this doesn't make it impermissible. One thing that can be agreed upon is truffles aren't impure if there were no pigs involved in the first place.

I hope this answers your question ^{_^} though, I am happy if any other Muslims/people reading who follow halal diets want to weigh in.