Ask any chef in town—a meatball is an easy sell. At Pizzeria Delfina, the Italian polpette are second only to the restaurant's namesake pizza. Further North at Chotto, a server says the juicy Japanese tsukune are a "must-try." On that note, almost every culture has a meatball, and San Francisco has representatives from more than several camps. Here, a bit of a cultural lesson by way of hand-rolled meat: from fiery Mexican albondigas to pomegranate-speckled Iranian kufteh tabrizi.