Daniel King
Google
This is a very small, but excellent restaurant. Having lived in Cologne for 3 years, when people would visit, I would always make it a point to take them here. The menu is simple, but has many typical German street foods. My favorite is the Spießbraten im Brötchen. It's slow roasted pork in a roll. Get it with onions. It's fantastic.
As well, they also have Wurst, Currywurst, and French Fries. The only things that may steer some away is that it's only standing room. They don't have any sit down tables.
Enjoy!