vegetarian xiao long bao?
The ones I had were made using mushroom and agar. I think you'd have to make solid blocks of agar (you could try adding some mushroom soaking liquid for more flavor) and put them on top of a chopped shitake mushroom kind of filling. I think this would be a hard thing to make at home.
I've attached a photo of one I had at Nanxiang Mantou Dian if it's helpful. I liked it for the novelty, but taste-wise, I'd rather eat more standard vegetable buns or dumplings.