Pesto is one of the most popular sauces in the world. The original recipe calls for seven ingredients, no more, no less: basil, extra-virgin olive oil, pine nuts, Parmesan cheese, pecorino cheese, salt, and garlic. We traveled to Genoa, Italy, where pesto was invented, to meet Roberto Panizza, owner of Pesto Rossi and the restaurant Il Genovese, and find out what makes each of the seven ingredients so distinctly Genovese.