Rejoice, all ye who must travel to Frankfurt for boring business travel. The search results for good chow are always depressing when you type in "Frankfurt", but here is a restaurant to save you!
My partner has been in Frankfurt for work over the past two months. A German co-worker turned him onto this place. It's two steps above the standard, traditional Frankfurt tavern, but still retains a wonderful, cozy atmosphere. For lack of an easier analogy I'm going to go out on a limb and categorize this joint as a gastropub (eeek, I know) a la The Spotted Pig in New York http://bit.ly/c5Y1q1 or the Anchor and Hope in London http://bit.ly/3ZGhmK only without the pretense, crowds or high prices. You can get local favorites like Handkas mit Musik (fresh cheese marinated with herbs) and Frankfurter Grune Sosse (eggs/potatoes/anything else in a creamy herb sauce), but also great spins on the classics like a curried lamb shank.
There are no tourists here. Bring a phrasebook that has a good food glossary (I'm sure there is an app for that, but http://bit.ly/ddVv2n). If it isn't TOO busy someone can probably help you through the menu. Do yourself a favor and call ahead for a table (this can be done the same day, no need to plan too far ahead). Take a cab there and ask them to come pick you up in a couple of hours or walk off that lovely dinner you just had.
Last night, three of us ate for less than 80 Euros (3 apps., 3 mains, 3 glasses of wine and a bottle of water). Here is a menu sampling:
Avocado salad with coriander vinaigrette
Steamed artichoke with fresh mayonnaise
Braised rabbit with fresh tagliatelle
Curried lamb shank with potatoes and vegetables
....and of course a variety of pork dishes!
There is also a great selection of beer, wine and Apfelwein. We didn't try the deserts, as Frankfurt has no shortage of ice cream shops and it has been very hot here this summer. I really can't recommend this place enough. It is definitely one of the best meals I've ever had in Germany.