I would step away from a substitution and go for a complete alternative that fits the occasion and the dietary conditions.
Ie a roast without a decent centrepiece isn’t worth it, and i have yet to try something that isn’t dissapointing i.e. a roast cauliflower ( it is delicious but **** me its portion of veg)
So i put forward.
Vegan bao buns*.
The buns are an absolute piece of piss to make, everyone can help.
Some sort of meatlike substance grated or shredded
Sauce
Various slaws and accoutrements
All on the table
Let the self serve pandemonium commence.
*At xmas we generally do left over roast bao buns which destroys the remains preventing “day 5 of christmas turkey” but other times of the year its normally vegan and its treated with the same gusto.