Local sourcing of food certainly is the trend among fine-dining independents, but multiunit chains have difficulty following suit. It isn't impossible, however. Pittsburgh-based Eat'n Park and Burgerville in Vancouver, Wash., also work with local farms to supply their restaurants with in-season produce.

Now Denver-based Chipotle says that, beginning this summer, 25% of the supply of at least one produce item for each of its more than 700 stores will be purchased from small and mid-size farms.

Ann Daniels, Chipotle's executive director of purchasing, says she doesn't believe the chain's food costs will increase as a result of the initiative. And as gas and transportation costs increase, buying from farms closer to stores could benefit the chain's bottom line.