Unlike modern Dortmunder beers, Adambier was a strong (about 10% abv), dark, sour beer, which was top-fermented and then aged in wood for long periods; it was always aged for at least a year, and often many years longer. Unlike sour Belgian beers, Adambier had very high hopping rates.
Some sources report that Adambier was brewed with significant amounts of wheat, while others report only strongly-flavored German malts. Modern homebrewed and commercial examples tend not to be brewed with wheat.
 History of Adambier
Adambier was a well-known indigenous beer style of Dortmund until it was eliminated by the changing tastes of German beer drinkers. The style was already losing ground to Munich-style dark lagers, which were faster and cheaper to brew, when the arrival of Pilsner beer, and later modern Dortmunder pale lagers, saw it decline even further. It is no longer brewed commercially in Germany.
 Brewing Adambier
Any attempt at brewing an Adambier should bear in mind that in the old days, malt was generally less modified, fairly dark and at least somewhat smoky from the wood-fired kilns used to dry it. Depending on how far back we try to go, a higher-kilned basemalt should certainly be used for a majority of the grist, with possible minute additions of smoked and roasted malts. Weyermann Munich malts serve nicely to provide a rich and malty base, and at the brewer's discretion a small portion of beech-smoked malt (rauchmalt) and roasted malt (e.g., Carafa II) can be used. Traditional German brewing involved long and complicated decoction mash schedules, wherein a portion (~1/3) of the wet malt was pulled from a very loose mash (1:1.75 grist:liquor) and boiled before reintroducing and thereby raising the mash temperature. With today's well-modified malts, it is largely considered unnecessary for conversion of starches, and indeed many modern commercial German breweries are switching to single-infusion techniques with acceptable results. Nonetheless, there are adherents who insist the melanoidin production from decoction mashes and the resultant malt profile in the finished beer cannot be acheived any other way. For those that do not have the stamina, will or equipment to produce a 10-hour triple decoction mash brew, there is the option of adding a small percentage (~3%) Weyermann Melanoidin malt to the grist to approximate a decoction. Gambrinous produces a "honey malt" that is said to represent German "braumalt" no longer available; with its intense sweetness a small addition would support a heavy malt profile. All of this will be furtheraided by a nice, long boil, say 90-120m, which has the added benefit of allowing for more thorough sparging and therefore better mash efficiency. Feel free to collect 140% preboil kettle volume, provided the pH and SG stay reasonable. At roughly 10% alcohol by volume, Adambier original gravity should be in the ballpark of 1.100, considering 70% apparent attenuation by the primary yeast and then further attenuation by other organisms in the aging barrel. Hopping rates are anyone's guess, but shooting for 40-60 IBU's would put the beer in the "well-hopped" category to which this style is known to belong. The hops used then are surely long gone, but Perle, Tradition, Brewer's Gold or Magnum will give a reasonably high alpha-acid contribution without an overload of vegetal mass. Any noble continental hop such as Spalt, Hellertau, Tettnanger, etc., will give a nice late-addition hop nose, though most of it may be lost during the aging process, and better added directly to the cask some time before packaging. The water in Dortmund has a high mineral, suggesting an addition of calcium carbonate and possibly a small amount of sodium carbonate (always depending on the base water profile, of course) to accuentuate the full-bodied hoppy character this style exhibits. An "obergärige" (top-fermented) beer such as Adambier should not be made with lager yeast as are most German beers, but with one of the few German ale yeasts available. As Dortmund isnt far from either Düsseldorf or Köln either an Alt or Kölsch yeast should suffice. Traditional Adambier brewing developed long before refrigeration, but it was common knowledge that beer produced in the cold seasons made a much cleaner product than those made in summertime. Both Alt and Kölsch yeasts are capable of fermenting in the 58-62° range, and will avoid an overly estery nose belying our modern ideas of a "German" ale - irrespective of the traditional realities that may have been. After full attenuation in primary, the bravest brewer will put the precious beer in a wooden cask and ignore it for at least a year, maybe four, to develop a natural acidity and veinous character. The somewhat less intrepid may still choose to add oak chips to a secondary aging vessel, and even perhaps innoculate with any of the various common pathogens found in wooden barrels, such as pediococcus, brettanomyces and most certainly lactobacillus. In fact, lactobacillus alone in secondary will produce a definite but clean sour aspect worthy of a modern interpretation, but if even that seems forboding, perhaps simply lactic acid added to taste will lend a passible sourness. This beer would likely have conditioned with the addition of actively fermenting beer (spiese) but if you aren't planning on brewing a batch every four years you can either force-carbonate in kegs or prime as usualy with a particularly healthy culture of alcohol-tolerant yeast; a Scottish strain might be particularly suitable for this given its very low ester production.
RECIPE (suggested amounts for 5g in parenthesis)
(18#) 75-100% Munich I [alternately sub up to 20% of that with wheat malt]
(3#) 10-20% Rauchmalt
(1#) 5% Melanoidin Malt [omit if doing a decoction mash]
(.5#) 2-3% Honey Malt
(.125#) .5-1.5% Carafa III
(4oz @ 7%AA) 40-60 IBU Hallertau Tradition, 90 minute (.5oz) Spalt Leaf four days prior to packaging.
WLP 036, and lots of it, in a well-oxygenated wort, pitched at 55° and allowed to rise to 64° over two+ weeks. In secondary, .5oz beech chips (previously sanitized in vodka) along with a pure lactobacillus culture, held at 50° for two months, racked again into aging vessel for at least 6 months. Prime with 4oz corn sugar and active 2oz (thick slurry) Scottish ale yeast culture, age cool for at least six months more, preferably two years.
 Competition Styles
Neither the BJCP nor the GABF recognize Adambier as a style; homebrewed versions should be entered in competitions as a specialty beer style. However, the Maltose Falcons -- a Los Angeles based homebrew club -- do recognize Adambier as a style in their own style guidelines. Adambier is in section 14, Northern European-Style Strong Beers, subsection 14.1 Dortund-style Adambier.
 Commercial Examples
The only known modern commercial example of Adambier is "Adam," brewed by Hair of the Dog Brewing Company in Portland, Oregon, in the United States.