Chances are you haven't seen it on the menu at your local Chipotle Mexican Grill (NYSE:CMG), but the company's new Sofritas protein option is holding its own against the fast-food mainstays of chicken, pork, and beef. The company said last week that the new ingredient already accounts for 3% of overall sales, despite being available at just 40% of its restaurants nationwide.

The reason it's not at more locations isn't a lack of broad demand, which you might expect for a vegan dish. Instead, it's that Chipotle hasn't been able to get its hands on enough supply of the organic tofu that forms the basis of the ingredient.

In the video below, Fool contributor Demitrios Kalogeropoulos talks about Chipotle's new vegan product, noting that it is selling surprisingly well among customers who normally eat meat and are open to trying nontraditional fast-food fare. Meanwhile, those of us whose local Chipotle doesn't yet offer the ingredient can look for that to change soon, as the company is busy securing additional supply for a more comprehensive rollout.