Knuckle Sandwich punches far above their weight. The tiny trailer outside of Ants Beer Cave in South Austin has only four sandwiches on the menu (plus a couple of sides), but that’s all they need.

We recently stopped by Knuckle Sandwich for lunch, one of the food truck options at Ants Beer Cave in The Yard. The big picture: The sandwich shop, which opened in August, has been all over social ...