Cupka's Cafe II on East Carson Street gets all the attention, but this is the original Cupka's Cafe, tucked away on the corner of 27th and Jane. (The sign outside says "Cupka's Cafe", the name "Richard Cupka Deli" is news to me.)
When I worked in the South Side Works, this became my favorite place to eat lunch, and the McCupka became my favorite hamburger to eat there. Patty hand-molded from ground beef, "special sauce", lettuce, and a wonderful soft bun. Since moving to New York I've been searching for it's equivalent but have yet to find it.
It's a small place, about four tables. The woman who would wait on us was sweet and I feel guilty that I do know her name. All the sandwiches are magnificent. Make sure you are hungry before you go.