Wa `alaykum As-Salamu wa Rahmatullahi wa Barakatuh
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
There is nothing wrong in consuming or using a product termed vegan.
In his response to your question, Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states:
You need not be nit-picking. Such an attitude is not the way of the Sunnah. Neither the Prophet (peace and blessings be upon him) nor his Companions (may Allah be pleased with them all) or any of the pious predecessors indulged in such nit-picking approaches.
The Prophet said, “Woe to those who are nit-picking in their approach to religion.” (Muslim)
He also said:
“This religion of ours is easy to practice; whoever makes it rigid will only defeat himself (i.e. he will end up giving it up).” (Al-Bukhari and Muslim)
You may consume products labelled as vegan unless you have a reasonable ground to suspect otherwise. This was the approach taken by the Prophet and the pious predecessors.
While respecting your concern to eat halal, I would advise you to focus on far more important aspects of the meaning of halal: the ethical living and practicing morality which are the true essence of the meaning of halal in Islam.
Almighty Allah knows best.