Used in Mexican and South American cooking to makes tortillas and tamales. Masa Harina Corn Flour is a soft, yellow flour made from dried corn kernels that have been cooked and soaked in lime in a process known as nixtamalization, to improve digestibility. The niacin and calcium naturally present in the corn are more available as well as protein. Mixed with water, it forms the dough to make tortillas and is an essential ingredient to prepare pupusas and arepas.