By THÉRÈSE MARGOLIS

Any true Mexican food aficionado will tell you, when it comes to tortillas, nothing compares to those made from Tarahumara blue maize.

The sweet, protein-rich grains of blue maize not only add an additional earthy taste to the corn masa used to make tortillas, but also an extra dose of antioxidants.

But since the Tarahumara maize is far rarer and far more pricy than Mexico’s traditional yellow corn, it is not commonly used in making tacos or other street food favorites.

But as of this month, El Farolito, the no-frills, made-to-order-in-front-of-you, late night haunt for taco-lovers of all stripes, is offering all the items on its menu with handmade blue tacos for an additional fee of just 2 pesos per order.

The blue tortilla menu, called “Juntos Iluminemos su Sonrisa” (”Together We Shall Light up Their Smile”), is now available in all nine El Farolito restaurants across the country, and is part of a fundraising effort being conducted by the taco giant in cooperation with the Fundación Iluminemos de Azul, a nonprofit foundation aimed at helping to create awareness about autism throughout Mexico.

Through July 31, every peso earned from the blue tortilla sales will go the Fundación Iluminemos de Azul, which offers public seminars on autism, promotes government programs to better serve the nearly 1 million Mexicans with autism, and works with parents of autist children to help them learn how best to encourage their children’s social and development skills.

During the four-month promotion, the restaurant chain is also selling special blue bookmarks for 20 pesos each, with the profits going to the autism foundation.

April 2 was World Autism Awareness Day.