Can I make vegetarian soup dumplings?
I have successfully made it with agar agar and I serve it at my restaurant in Lucknow, India. I call it Soup Burst Momo (TM) It stays liquefied if consumed within 5 mins of steaming. After that it slowly starts to thicken. Carageenan will give you better results. 

The only problem I've faced is that you have to steam it instantly after folding it, otherwise te pastry gets wet due to osmotic movement of water from gel to dough. 

Although, it could possibly be addressed by using frozen gel and then against flash freezing the folded dumpling instantly.