So, I asked "the Germans" what they thought the secret to "German lager flavor" is. The consensus was to ferment under 10*C, lager at 0*C (for 5+ weeks), pitch a lot of yeast, if possible. Some said Pilsen-type water was fine, some suggested harder water would help.
I told them that I use decoction mashes, and they assumed I didn't know what I was saying, apparently because decoction mashing is insane. German homebrewers step-mash everything, but as far as I can tell, they never use decoctions. Some think of decoction as a sort of old-fashioned gimmick to sell beer.
Here's one response I found interesting (my translation, from http://hobbybrauer.de/modules.php?name=eBoard&file=viewthread&tid=16789
Decoction mashing came from Bavaria. In the 19th century, Anton Dreher of Schwechat (near Vienna) invented lager beer as it is known today. He traveled to England, which was at that time the leader in malting, and brought their techniques to Schwechat. He was also influenced by Gabriel Sedlmeyer, from Munich, with whom he worked closely. Also from Bavaria was Joseph Groll. He went to Pilsen, in Bohemia, and invented Pilsner Urquell. That beer was brewed with Bavarian decoction.
We have these three legendary brewers to thank for the triumph of lager in Germany, and later the world. Lager soon spread and replaced many varied types of beer in Germany. Before this, Germany had a lively brewing industry, with a great diversity of ales. Because of lager, the majority of those ales are now extinct.
The decoction procedure was very popular in the 19th century. Today, decoction is long gone. Almost every brewer uses direct heat. They instead use kettle mashing (direct heat) or hot water infusion. Usually they use the high-short process (hochkurz) because time is money.
In Bohemia/Czech Republic decoction is still popular. Pilsner Urquell is supposedly brewed using the original recipe from Joseph Groll.
In Germany, only a few old, traditional breweries use the expensive decoction process for their flagship products. This is more or less for prestige, to compete in the difficult German beer market. For example, the Andechser Doppelbock Dunkel. It is brewed with a triple-decoction. A beautifully aromatic Doppelbock, is it therefore in the “Top 100” beers on Ratebeer.
The small craft breweries in Germany also try to preserve the old brewing processes. The large breweries copy these beers, and make them in a cost-effective manner. [I'm not sure I translated that correctly, I'm not sure if the big brewers copy the craft brewers, or vice versa. "Die kopieren auch nur die Großen um einigermassen kostengünstig produzieren zu können."]
I had a great decocted beer last year at the Kommunbrauern in Ummerstadt. The small brewhouse was built in the 19th century, and has since been preserved by the locals. The mash was boiled for 90 minutes. The wort was boiled for 5 hours. That beer was awesome, crisp and malty, without much carbonation.
So, it is still there, that “old lager flavor,” but you must look with a magnifying glass to find it.
Here's a video of Brauerei Ummerstadt (German not required, but it helps): http://www.youtube.com/watch?v=fYm-LoothK0