McDonald's brought the hamburger to the world... and now the world is pushing back, starting in India. Bowing to local pressure, Mickey D's is opening its first meat-free restaurants ever in the South Asian country. How drastically will the planet's largest burger chain transform its menu to venture into uncharted vegetarian territory? Here, a brief guide:

A vegetarian McDonald's? Really?
Yes. McDonald's has always tried to tweak its menu to suit local tastes, a particularly daunting challenge in India, where up to 42 percent of the population avoids meat altogether. India's Hindu majority, which considers cows holy, avoids beef. (McDonald's has never served beef in India since it opened its first outlet there in 1996.) The country's large Muslim minority shuns pork. (McDonald's tried serving lamb burgers, but those didn't go over well. Its popular Maharaja Mac burgers are made with chicken.) Both Hindus and Muslims, however, can enjoy meat-free fare equally. "There is a big opportunity for vegetarian restaurants," says Rajesh Kumar Maini, a McDonald's spokesman in northern India.

Is it really worth the effort?
It could be. India represents a huge, mostly untapped market for McDonald's. The country has a population of 1.2 billion, currently served by only 271 McDonald's restaurants (the chain has 33,000 worldwide). India has a $12 billion a year fast-food market, currently dominated by local independent restaurants, with just 5 percent going to chains like McDonald's. That share is expected to double by 2016, however, as a growing middle class and cost-conscious families give chain-fare a try. McDonald's naturally wants to get in on the action.

Where will the first vegetarian McDonald's be?
McDonald's is opening its first meat-free restaurant in Amritsar, a northern Indian city that is home to the Golden Temple, the holiest site of India's Sikh minority. Meat is barred in the temple, so McDonald's figures an all-vegetarian menu is the best way to attract hungry pilgrims. The company is also opening a second vegetarian outlet in another busy pilgrimage spot, the entirely vegetarian town of Katra, the base for Hindus visiting the Vaishno Devi mountain shrine. "A vegetarian [outlet] makes absolute sense in the places which are famous as pilgrimage sites," Maini says.

Will McDonald's have to cook up a veggie menu from scratch?
Hardly. The company's menu in India is already roughly 50 percent vegetarian, and its biggest seller is the McAloo Tikki burger, which has a spiced potato-based filling and accounts for a quarter of total sales. Another popular dish is the McSpicy Paneer, which features a patty of traditional Indian cheese. Still, says Maini, the company will have to cook up a lot of new vegetarian options.

Is this the start of a vegetarian fast-food revolution?
That might be a stretch, says Matthew Yglesias at Slate, but if this attempt to penetrate the market in India "takes off at all I imagine it'll provide a valuable testing ground for the general concept." The U.S. has 15 million vegetarians — that's a bigger potential market than the entire population of Belgium, Greece, or Pennsylvania. "A vegetarian fast food concept that works could have legs." Fine, you eat it, says Adharanand Finn in Britain's Guardian. As a vegetarian, I'll stick to my "holier-than-thou" lifetime ban on ever entering a McDonald's. Although... the McAloo Tikki burger "sounds tempting."

Sources: BBC News, Financial Times, FOX Business, Guardian, Slate