Last week, we were at a friends’ house for dinner when talk turned to the Cooking for Solutions conference I was headed to at the Monterey Bay Aquarium. “It’s about exploring ways to create a more sustainable food chain,” I said. Brows went up. Heads tilted. And finally the question was asked: “What, exactly, does sustainability mean?”

The answer, it turns out, isn’t so easy to pin down. Over the past few years I’ve come to think of sustainability as a system of practices that is healthy for the environment, economically viable and a positive influence on the community that can be sustained over the long haul. Admittedly, it’s not cut and dry. But maybe, as Wes Jackson, president of The Land Institute, suggested at the conference, it isn’t meant to be.

Wes suggested that “sustainability,” like “justice” and “health,” is a value term. While we may not be able to pin down precise meanings for these words, we nonetheless organize entire societies around the concepts they embody and fight tooth-and-nail to defend them. I’d argue that a core ideal of sustainability is making sure we do things in a way that will preserve something for future generations.

That can all sound vague and stern and solemn, but bring sustainability to the kitchen and you’ll find color and life and flavor. When I make this sandwich with spring radishes and arugula from the garden and everything else sourced locally, for instance, it brings an added depth of pleasure to know that I’m nurturing the earth and supporting my local farmers . . . and you can’t get much more economical than bread and cheese.

My challenge this week isn’t about buying local or buying organic or anything that dogmatic. It’s simply about encouraging you to look at the effect your food purchases have–on the environment, on your community, on your budget. Because ultimately, sustainability has to be about what you value if it’s to have any value at all.