Pilsners dominate Americans’ perceptions of Czech beer, but the Central European country has a dark, beery secret. The second most popular brew in the Czech Republic is near-black tmavé pivo, or “dark beer,” a brewing style that actually predates pilsner — and upstages it in some Czech taverns.

At Prague’s oldest brewery, U Fleků, founded in 1499, you’re only going to drink tmavé pivo with your goulash. U Fleků doesn’t brew any other kind.

For those of us who love Czech pub culture, tmavé pivo has long been something of a local secret. The style wasn’t even listed in the guidelines of the Beer Judge Certification Program, a set of style descriptions for homebrewers and pro brewers alike, until a revision in 2014. (Full disclosure: I helped review the Czech sections of those guidelines before publication.)

One of the most high-profile brewers to start talking about Czech dark lager was Michael Tonsmeire, who wrote about tmavé pivo on his popular Mad Fermentationist blog at the end of 2015.

“I think the entry-level description is, think of a Czech pilsner versus a German pils. Now think of a schwarzbier,” Tonsmeire says. “Tmavé pivo is like the Czech version of German schwarzbier. It’s a little rounder, a little maltier, a little smoother, maybe, with a little more body.”

That fuller body can make a tmavé pivo especially appealing in cold weather, when you’re thirsty for something a bit richer than pale lager. (This might be the reason for the local legend which holds that tmavé pivo leads to larger breasts, and is thus an ideal drink for women. This idea is given surprisingly serious consideration in leading Czech newspapers.)

With just a touch — often only a hint — of roastiness, a good amount of complexity, and well-balanced malt sweetness, tmavé pivo also goes extremely well with traditional Czech recipes like goulash or svíčkova na smetaně, or roast beef tenderloin in a root-vegetable-scented cream sauce.

Ivan Chramosil probably knows more about tmavé pivo than anyone on this planet, having served as the brewmaster at U Fleků for over 44 years before finally “retiring” in early 2016. He now consults at different breweries, including U Supa, in Prague’s historic Old Town.

When I stop by U Supa to ask Chramosil for a basic tmavé pivo recipe, he spells out the answer like it should be obvious: about 50 percent Pilsner malt, between 30 and 40 percent Munich malt, up to 15 percent of a caramel malt like CaraMunich, and at most 5 percent of a very dark malt like Weyermann’s Carafa II Special. That last percentage of dark malt, he notes, can also include a small portion of something like Weyermann’s CaraAroma, though he warns about overdoing things.

“You have to be very careful with the roasted malt,” Chramosil says. “It should affect the color, but not really the taste.”

In terms of bitterness, Chramosil suggests around 25 IBUs for the most common tmavé pivo with around 5 percent alcohol, and he specifically recommends Czech Saaz hops. (A typical tmavé can have as little as 3.8 percent ABV, and up to 6 percent or so in what the Czechs call “speciál” beer.)

Just as important as the ingredients, Chramosil says, is the process.

“The fullness and the drinkability of Czech tmavé pivo is done by decoction mashing,” he says. “This should not be an infusion mash. It really has to be a decoction mash.”

And that might be why tmavé pivo is not seen too often outside of the Czech Republic: Most American brewpubs are not set up for decoction mashing, and many brewers outside of the Czech Republic are simply not comfortable with the process.

(Here in Prague, visiting brewers often ask about Czech decoction methods. When they hear that it means removing about a third of the mash to a different kettle, raising it to the boiling point, holding it there for 20 minutes or so, and then returning it back to the main mash, a few have looked like I was describing an obscure and possibly dangerous form of black magic, one which they would prefer not to hear spoken of ever again.)

And yet tmavé pivo seems to be growing, both in terms of exports from the Czech Republic, and those made by a few American brewers and homebrewers willing to practice those dark arts. Notch Brewing in Massachusetts now makes a celebrated tmavé pivo, as does Devil’s Backbone in Virginia.

Michael Tonsmeire is currently building out his Maryland brewery, Sapwood Cellars, and speaks glowingly about tmavé pivo.

“They hit that great balance, for me, of being easy to drink but not boring,” he says.

Sapwood isn’t actually planning to make one, Tonsmeire says, focusing instead on hop-forward beers and mixed fermentation. But when he starts describing what he likes about tmavé pivo, you get the impression that he just might change his mind. Until then, it will be our secret.

Five to Try

Koutský 14º Tmavý Speciál

This rare bird from the near-mythical Pivovar Kout na Šumavě is technically a tmavý speciál, or dark strong beer, with a hearty malt backbone and 6 percent alcohol.

Bernard Černý Ležák

The Bernard family brewery’s “black lager” is arguably the Czech beer connoisseur’s favorite among the most widely available Czech darks. Spicy and nicely balanced.

Budvar B:Dark

The other beer from the other Budweiser, this slightly spicy, moderately bitter tmavé comes from the state-owned brewery in the Czech town known as Budweis in German.

Krušovice Černé

Another dark beer flying under the “black” label, this lower-alcohol dark beer from Heineken-owned Krušovice is refreshing enough for warm weather.

Velkopopovický Kozel Černý

Part of the Pilsner Urquell group of breweries, Kozel’s food-friendly dark lager is probably the most widely available tmavé pivo around the world.