My own sweet pepper crop was largely a failure this summer—voles, sunburn and other excuses. Backup plan: the farmers’ market. The heaps of fleshy red bells at the Napa market made me hungry for kopanisti, the Greek feta spread with sweet and hot peppers. I sort of knew how to make it, and there are plenty of recipes online, but I wanted input from my go-to Greek-food authority, Sotiris Kitrilakis. And that’s how I learned I didn’t know anything about kopanisti.