Tomatoes are a cornerstone of Italian cooking and there's one particular tomato that's prized and priced above the rest-- the San Marzano tomato. "They get this very low acidity, PH is around 4.5, and they're sweeter," said Elia Gambaccini, whose family owns Cafe Baonecci in North Beach. Gambaccini says San Marzano tomatoes make for great pizza and pasta sauce.

"They're very nice."
But the legitimacy of San Marzano tomatoes in American grocery stores has long been questioned. A new class-action lawsuit, filed by three Northern California home cooks last week, alleges that New Jersey food company Cento is peddling imposter San Marzano tomatoes to command a higher price.