Chocolate. It's not the first association you might make with Cologne, home of the famous "eau de".
Yet my first stop on a culinary trail of this little-known gourmet treasure takes me to a Chocolate Museum. And it's not some small affair tucked down a side street either. In 1993, the late Dr Hans Imhoff, a director of the Cologne-based Stollwerck chocolate company, spent the equivalent of €£32m opening a massive three-storey steel and glass edifice on the banks of the Rhine.
My guide explained that at its peak, before the Second World War, Stollwerck was the biggest chocolate producer in the world, employing upwards of 12,000 people, making the southern side of the city the German equivalent of Bournville, or Hershey, Pennsylvania. Yet now, the only chocolate made here is in the small show-factory on the second floor of the museum where you can see the mixing, rolling, conching (stirring over heat) and packing processes up close.
The museum is full of little delights, from the mini-rainforest where they're attempting to cultivate their own cocoa beans (no luck so far) to the collection of beautiful art-nouveau chocolate-vending machines. But best of all is the delicious hot chocolate and chocolate gateaux on sale at the riverside café, made with the museum's own chocolate.
Ninety per cent of Cologne was destroyed or damaged during the Second World War. Apart from a few notable architectural exceptions, such as the Kölner Dom, one of the largest and most impressive High Gothic-style cathedrals in the world, and the beautifully austere Kolumba museum of art, there's a functional look to much of the rebuilt city. Which makes a tour around the hugely atmospheric and characterful brauhaus (brew house) bars such a treat.
Many are huddled around the picturesque Old Town, but you'll need to head to the bar and nightclub-packed Friesenstrasse on the north-eastern edge of the city centre to find the last Cologne brauhaus with its own on-site brewery. Established in 1883, Päffgen produces 6,000 hectolitres (132,000 gallons) a year of Kölsch, Cologne's signature pale, hoppy beer.
There's no bar lined with flashy logoed beer pumps here. Instead, the Kölsch is drawn directly from mini wooden barrels stacked on a drum stand in the entrance to the handsome wood-panelled dining room.
Served at cellar temperature, Kölsch is smooth, refreshing and dangerously easy to drink. As soon as I'd emptied one of the slender, rod-like stange glasses, it was instantly replaced – by an aproned waiter (known as a Köbes), who carried a dozen or so beers on a circular metal tray called a Kranz, and marked off each drink with a pen on the back of a beer mat. Fortunately, a simple but delicious lunch of bratwurst sausage with sweet mustard and a rye bread roll was hearty enough to soak up at least some of the alcohol.
At La Vision restaurant in the Hotel im Wasserturm, they've elevated many of the same ingredients you'd find in a rustic brauhaus dish to new heights, and not just because the Michelin-starred dining room is on the 11th floor of a converted water tower. The marinated herring with boiled potatoes I'd seen on the menu at Peters Brauhaus in the Old Town, became herring in aspic topped with caviar, served with coins of fried potato and a cucumber and dill sorbet.
With more than 3,000 restaurants and bars, there's real depth and diversity to the city's culinary scene. But Cologne is also a short train and taxi ride away from no less than two three-Michelin-starred restaurants; Dieter Müller and Vendôme in nearby Bergisch Gladbach. Both are part of the Althoff hotel group, which has been known to chauffeur its more fervent foodie guests between the two restaurants for lunch and dinner on the same day. I was a little more circumspect, making two separate trips and leaving six months rather than six hours between extravagant, blow-out meals.
Although both were luxurious, multi-course affairs, they couldn't have been more different in style. Eating Müller's signature salad of freshwater crayfish, calf's head, cauliflower and herbs in the Schlosshotel Lerbach's conservatory dining room overlooking the converted manor house's acres of private parkland, I could almost have been dining in an English country-house hotel. At the ultra-modern Vendôme in the grounds of Schloss Bensberg (a jaw-droppingly impressive baroque castle), dishes such as mottled ravioli of mascarpone with Périgord truffles and aged balsamic vinegar are as elegant and cutting edge as anything you'd find in London, Paris or New York.
But there's only so much exquisite fare one man can take, so it was time to seek out the darker side to Cologne's culinary identity. Literally translated, currywurst means "worst curry in the world", or at least it should. How else to describe a sliced bratwurst sausage drowned in a thick Vesta-like curry sauce, dusted with curry and chilli powder and served with chips and lashings of tomato sauce and mayonnaise on the side? But there's a reason why the Currywurst Sepp stand on Ehrenstrasse attracts a crowd, even in the middle of the afternoon. That gloopy crime against gastronomy is, whisper it, totally delicious.
How to get there
Germanwings (0906 294 1918; germanwings.com) flies daily from London Stansted to Cologne, from £13.99 each way. Hotel im Wasserturm (00 49 221 20080; hotel-im-wasserturm.de) charges from €225 (£197) per night for double room and breakfast.
German National Tourist Office (020-7317 0908; germany- tourism.co.uk).