For most people, Chipotle Mexican Grill (NYSE: CMG) may simply bring to mind fast, tasty, densely stuffed burritos -- and a valuation that's no less weighty. However, this company's packed with a lot more to savor than many investors or customers may realize.

Beyond its fast-food Mexican fare, Chipotle pursues a mission of "food with integrity." As the company explains, it aims to serve "the very best sustainably raised food possible with an eye to great taste, great nutrition, and great value." Chipotle seeks to use as many ingredients possible that limit antibiotics and synthetic hormones, focus on locally grown and organic produce, and use sustainable production techniques.

Chipotle's strong stance on these issues is not only a do-gooder initiative. The "food with integrity" strategy also helps differentiate the company from fast-food rivals like Wendy's/Arby's (NYSE: WEN), Panera (Nasdaq: PNRA), and former parent McDonald's (NYSE: MCD).

Last year, Chipotle cannily promoted the documentary Food Inc., which sought to expose unappetizing aspects of factory farming. That film did a lot to raise the public's awareness about the mass production of food by giant, powerful corporations like Monsanto (NYSE: MON). (Monsanto wasn't exactly an enthusiastic fan of the film, issuing rebuttals to many of the documentary's allegations through its website and other channels.)

Chipotle's not the only company with strong socially responsible initiatives built into its business model. Whole Foods Market (Nasdaq: WFMI) and Green Mountain Coffee Roasters (Nasdaq: GMCR) also notably pursue beneficial practices, and even behemoths like Wal-Mart (NYSE: WMT) have begun to realize that consumers now care more about good corporate citizenship. In response, Wal-Mart increasingly offers locally grown produce for sale, and it's formulating a sustainability index for its suppliers, among other efforts.

My Foolish colleague Rick Munarriz served up three reasons to buy Chipotle last week, but I'll throw in a fourth for dessert: It fits within the universe of socially responsible companies driven to do well by doing good. That makes Chipotle a savory choice for investors who seek positive returns in both the fiscal and social sense from the stocks they purchase.

Join us for a live hourlong chat with Chipotle co-CEO Montgomery Moran on Tuesday, Dec. 14, at noon ET. It'll be mighty tasty!