Cant help with whether or not you can get it at dinner - I assume you can (Disney is VERY accommodating), but just wanted to add that I had this in December for the first time and absolutely LOVED it!!!
I just didn't want a big steak on our last day when we had to get on the plane in a few hours, so I ordered the burger and it was amazing. Coupled it with the macaroni and cheese and I was in heaven!