While any style of low-hopped, low-IBU beer can be used as a base for sour beer, only in the past few years have brewers found an audience for sours built from dark and roasty stouts.
Cue Placentia, California’s The Bruery, whose Tart of Darkness has become a flagship of the nascent style. The base beer is a 5% ABV stout, and the aggressive souring overpowers much of the typical stout character, but as a sour it delivers a great balance of sour notes with an attractive dark body.
Austin, Texas’s Jester King brewery goes a bit wilder, incorporating its native yeast into a mixed fermentation for the beer it calls Funk Metal. At 8.2% ABV, it’s a heftier beer, and retains the roast and chocolate flavors one expects from a stout while layering in a healthy dose of sour.
Jolly Pumpkin offers additional sweet notes on top of the expected roast and sour in its hefty 8.1% ABV Madrugada Obscura.
On the blended side, New Belgium’s Clutch dark sour pairs 80 percent of a strong stout with 20 percent of its soured dark lager, Oscar, yielding a 9% ABV beer with more subtle sour. It’s a fitting collaboration with the band of the same name.
Brewers tackling sour stouts have to walk a fine line given the naturally high acidity levels of dark malts, but as these examples show, darker base beers can provide a fantastic showcase for souring cultures.