The current co-owner of Rao’s, Frank Pellegrino Jr., told Bon Appetit in 2015 that the famous marinara sauce was created by his grandmother many years ago, and the sauce you buy in stores is the same recipe served in his restaurants. The ingredients are common, but correctly choosing the main ingredient—tomatoes—is important. Try to find San Marzano-style whole canned tomatoes, preferably from Italy. They are a little more expensive than typical canned tomatoes, but they will give you some great sauce.