1Bring a small pot of water to a boil. Score the bottom of each San Marzano tomato with a small 'x'. Briefly blanch the San Marzano tomatoes in the boiling water for 30-60 seconds until the skin begins to peel. Immediately transfer them to an ice bath to stop cooking. Once cooled, peel the San Marzano tomatoes, remove the seeds, and roughly chop the flesh.