If you used a domestic olive to sauté veggies for dinner last night, chances are it came from California. And, if the label says “extra virgin,” chances are you have no idea how hard-won those two words actually are. I certainly didn’t, until I talked with Alison Carroll, founder of California’s latest small-batch artisanal olive oil, Wonder Valley. (Find out why she lives near Joshua Tree, far from her olives here).

Years after the big exposé that revealed the ugly truth about imported olive oil (basically, that often what’s in the bottle has little to do with what’s on the label), California olive oil producers banded together to create rigid standards for oil sold here. It’s a heated issue, and I’m no expert. But I am a home cook who likes to buy local products—and I like to understand why I pay a premium for them. Here’s what makes Wonder Valley oil—made from olives grown and pressed in the farm belt north of San Francisco—so special.

What “extra virgin” actually means: “It means that it’s the highest quality of olive oil—nothing has gone wrong with it. Nearly 100 percent of California producers pay to have their oil submitted to a tasting panel for lab analysis every year to make sure it meets the standards set out by the California Olive Oil Council. Otherwise they aren’t legally allowed to have that phrase on their label.”

The early years: “We use a mix of taggiasca, ascolano, and arbequina olives. Very few people grow ascolano olives, but arbequina is the most common olive in the world. They’re all picked while still green. The younger the olive, the more polyphenols, which is that fountain of youth part you hear people talking about.”

Getting squeezed: “Harvest usually happens in November. Then you have 24 hours to get picked olives to the mill because this is when the problems can happen. Within hours, the olives are pressed. The oil is then filtered and sits for about a month to settle before being bottled.”

The dark side: “We import our bottles, then use a custom matte black finish because light (along with heat and time) are olive oil’s nemeses. You can make the best oil and then you just put it in a clear bottle and it just kills it.”

Want more? Check out an olive-oil expert’s tips for a trip to Greece!