They are Chinese steamed buns (do a search on google images)-- I don't have any pics. I think you get two in an order, but can't remember for sure. It's bread that is filled with meat or veggies.
I grew up eating these, and I found the ones there to be so-so. Definitely not a counter service meal-- should be a snack option in my opinion. They are on the small side.
Not quite sure why they place is called "Herbie's," other than the fact that it is located outside of the Lights, Motors, Action! show. It is just a trailer or lunch truck. I find it a rather strange offering on Disney's part.
I'd pass on this one, unless you'll be in the area anyway.
They sell slushies and pretzels there too.