Then I can recommend you
Uncle Sams which is a really tiny burger restaurant where you can eat really delicious homemade American food for a good price and drink all these cool stuff that you can't get in every super market (lipton icetea sparkling, dr. pepper, etc.).
The cool thing is that you can order burgers by weight, you don't only have normal and big burgers and you don't get these prepared, frozen crap meat burgers.
<- This is what I put into my stomach ;-P