LA PAZ (Reuters) - A Bolivian avant-garde restaurant hopes this week to serve a well-known non-paying customer and receive a holy seal of approval for its new creation: a quinoa-based communion wafer.

Chefs at the restaurant, Gustu, in La Paz expect Pope Francis to receive the wafer during his visit to the Andean country later this week, the second leg in the Argentine pontiff's three-nation "homecoming" tour of South America.

The idea came from a group of quinoa producers. The restaurant's chefs said the wafers have been delivered to the government to give to the pope.

"I'm quite nervous about what he will think," said Monica Marquez, the restaurant's 25-year-old pastry chef with a small tattoo of the Christian cross behind her ear.

Gustu is the brainchild of Danish chef Claus Meyer, widely known for his restaurant Noma in Copenhagen which is ranked third in The World's 50 Best Restaurants list. On the menu is Llama tartare and trout from the water of Lake Titicaca served with llullucha, a South American seaweed. The restaurant opened in 2013 to wide acclaim.

Unlike neighboring Argentina and Peru, Bolivia is not especially known for haute cuisine. With Gustu, Meyer sought to reinvent the country's culinary traditions and take them global. On its menu are Bolivia's little known wines and liquors grown at high altitude in the Andean highlands.

The quinoa wafers cannot be used in communion like the unleavened wafers prepared by laymen. But they could raise the profile of the Bolivian seed.

Gustu's chefs experimented for days before settling on a recipe using ground black, red and white quinoa to produce different colored wafers.

"We thought we'd just see what would happen. We're used to experimenting with new recipes," Marquez said.

Quinoa, called a "super food" because it is a rich source of vitamins and minerals, has been the staple of Andean farmers for thousands of years but has taken health-conscious Western nations by storm more recently.

(Reporting by Sarah Marsh; Editing by Richard Lough and Jeffrey Benkoe)