The cardamom substitution would be the primary deal breaker. That’s one of the big stars of this show without which it simply wouldn’t be the same thing.
I don’t really know how tofu performs when boiled, it might potentially work with the firm stuff. You could possibly switch the beef for chicken mince if you want to, Quorn mince would work, black beans might be entirely possible substitution too.
Not sure about making it entirely vegetarian however as the broth is quite important, veggie broth would change the profile a lot. Maybe it could be pulled off if you compliment it with a few drops of dark soy sauce. Maybe adding a piece of star anise to help offset the loss of umami flavours the beef brings, but not so much that you get the licorice flavour coming through.
Edit: I almost forgot to add, if it’s available on your market make sure you get Brazilian beef. Preferably from a cow who has personally burnt down rain forest. The more ecological disaster wrought the tastier the meat!