Chef Shack is a buzzing food mobile located at the stylish Mill City Farmers' Market. The food is basic and American, but fairly well-prepared with high quality ingredients.
I had a vegan beer brat ($5) which was, other than the fries, the only vegan thing available. The brat was pretty good: nicely flavored (hickory smoke?), filling and simple. None of the condiments looked too interesting to me, though all of them are vegan (except for the bacon ketchup).
If Chef Shack had more vegan options, I'd give them a higher rating and probably come back for more. For lacto-ovo vegetarians, they also offer a cheese-filled veggie burger, as well as Indian-spiced donuts and a fancy nacho dish.
The prices are pretty high considering the style and quantity of food, but the quality is high, so maybe it's worth it.