Pesto became a staple in the Ligurian culinary tradition, with each family often featuring its own pesto recipe (with slight differences to the traditional ingredients). This is the main reason why pesto recipes often differ from each other. In 1944, "The New York Times" mentioned an imported canned pesto paste. In 1946, "Sunset" magazine published a pesto recipe by Angelo Pellegrini. Pesto did not become popular in North America until the 1980s and 1990s. Pesto is traditionally prepared in a marble mortar with a wooden pestle. First, garlic and pine nuts are placed in the mortar and reduced to a cream,
Bread sauce or chicken. The use of slightly stale bread is optimal, making it an economical way of using up leftover bread. The sauce is easy to make and uses readily available ingredients. Bread sauce can be traced back to at least as early as medieval times, when cooks used bread as a thickening agent for sauces. The utilisation of bread in this way probably comes from cooks wanting to use up their stale bread who discovered that it could be incorporated within sauces to make them thicker. Turkish cuisine also features a cold sauce made from breadcrumbs mixed with pounded walnuts