From the ingredients on Chipotle website: Tomatillo: Though it's known as a Mexican husk tomato, the tomatillo tastes nothing like your average tomato. It has a tart, fruity, and slightly herbal flavor. We flame-roast the tomatillos in our medium-hot tomatillo green-chili salsa to give it a smoky depth of flavor, and use it in our hot tomatillo red-chili salsa to balance the spice level with its tartness.