With the help of a team of scientists from Stanford University, Caltech, and elsewhere, Beyond Meat spent more than three years developing its Beyond Burger, a veggie burger that aims to closely simulate the feel of eating meat. It hit the aisles at Whole Foods in Boulder, Colorado, last month, making headlines and selling out within a few days .

“Three or four years ago, there would never have been this reaction. There’s a shift occurring.”

But its biggest challenge to success still lies ahead. It will depend on the company’s ability to convince grocery stores to put it in a place no veggie burger has gone before: the meat aisle.

The Beyond Burger, made primarily from pea protein and coconut oil (with a dash of beet juice for redness), is unique among plant-based burgers so far in that CEO Ethan Brown wants to only sell the “raw,” fresh-packed burger in grocery stores that will place it in the refrigerated fresh meat case.

One day, he envisions this space will be called the “protein” aisle, in the same way that dairy aisles have made room for almond milk, soy milk, and a proliferation of other alternative products alongside the traditional cow variety. But that’s not an easy sell, even to the largest health-conscious chain in the country. “We approached Whole Foods in 2012-2013 with a chicken product. They didn’t agree to it. They weren’t ready, the product wasn’t ready,” says Brown.

This time, with the Beyond Burger, Brown talked to Theo Weening, the global coordinator for meat buying at Whole Foods, and met with him in Maryland. Whole Foods has a decentralized structure, where different regions can make different buying decisions. Weening was sold this time, and he called a meeting with all regional meat buyers and walked them through the product, and the idea of putting it in the meat case. Tom Rich, the Rocky Mountain region vice president of purchasing and distribution, ended up agreeing to it–hence the Colorado-only debut.

Right now, there aren’t concrete plans for further distributions beyond the Rocky Mountain region or with other retailers, but Brown is pushing discussions as Beyond Meat prepares to open up a new production facility in Dallas to meet demand. He is optimistic he can convince other grocery retailers, as Beyond Burgers have been flying off the shelves in Colorado already. And now, more than a few years ago, consumers are waking up to the health and sustainability benefits of reducing their meat consumption.

“I can tell you that three or four years ago there would never have been this reaction,” says Brown. “There’s a shift occurring.”