They made their mark by selling real burgers and now they are changing it all?

McDonald’s Corp will offer its first-ever 100 percent organic beef hamburger for a limited time in Germany, as a growing number of global diners demand food that is more natural and less processed.

From Oct. 1 to Nov. 18 McDonald’s will offer “McB” burgers, made with organic beef sourced from organic farms in Germany and Austria.

The move from the world’s biggest restaurant chain by revenue comes as it is revamping food-sourcing practices as part of new Chief Executive Steve Easterbrook’s effort to transform McDonald’s into a “modern, progressive burger company.”

Germans, known for their love of sausages, are eating less meat and more vegetarian food as concerns grow about health, animal welfare and the environmental cost of livestock farming.

In Germany, beef certified as “organic” must come from cattle that eat organically grown feed and graze on pasture where synthetic chemical fertilizers and pesticides are not used.

“We have made a great effort to secure sufficient quantities of meat which satisfies the organic requirements and our own quality claims,” said Holger Beeck, chief executive of McDonald’s Germany.

McDonald’s has tweaked menus and worked to improve service in Germany, one of its topEuropean markets. The company’s quarterly sales at established restaurants in Germanyrecently grew for the first time since the middle of 2012.

A McDonald’s U.S. spokeswoman declined to say whether the company would roll out the burger to other markets.

Sales at McDonald’s have slumped, in part due to competition from newer chains including Chipotle Mexican Grill Inc, which for years has offered meat from animals raised without hormones and antibiotics.

McDonald’s USA said in March that within two years, it would stop buying meat from chickens raised with antibiotics vital to human health.

That move was cheered by public health and consumer advocates, who are concerned that overuse of antibiotics in meat production is contributing to rising numbers of life-threatening human infections from antibiotic-resistant bacteria dubbed “superbugs.”

Still, a shareholder group thinks the company has not gone far enough. It is renewing its call for McDonald’s to stop buying any meat from animals raised with antibiotics vital to fighting human infections.

Earlier this month, McDonald’s said its 16,000 U.S. and Canadian restaurants would switch cage-free eggs by 2025.