Many people think that one of the best ways to eat sustainably is to eat local food; the term "locavores" has been coined to describe people who eat all or most of their food from local sources. Eating locally means less fossil fuel burned to get the food to you — as an added bonus, it also supports your local economy. If you're industrious, you can obtain and prepare local food from the Davis Farmers Market, from Fruit and Vegetable Stands, from a CSA box, from the Meat Lab, or by reading carefully the signs at grocery stores such as the Davis Food Co-op. Or you can grow it yourself! (It doesn't get much more local that that).
For those that are less industrious, here are some restaurants that emphasize local food:
You might also be interested in Local Products.