This story is by Reginald Bretnor using the pen name Grendel Briarton.
Ferdinand Feghoot explored the system of the star y-Turista during the Third Franco-Mexican Empire. The expedition was sponsored by His Cosmic Majesty, Maximillano Ixthuatl XXII, who decreed patriotically that only Mexican food might be served aboard ship.
In 3002, Feghoot returned, and was ushered directly into the Presence. “What did you find?” asked the Emperor.
“Sire,” replied Feghoot, “Most marvelous of all are our Ixixixangos.” He pointed to a couple of creatures who looked like vitrified anteaters and clanked when they walked. “All other life-forms are either carbon or silicon based. Only the Ixixixango has a chemistry based upon both, and requires both for its substance.”
“You mean they can’t eat what everyone eats?”
“No indeed. We fed them ground glass and meat.”
“Ha!” cried the Emperor. ” So that’s how you follow my orders, Fernando Feghoot. Ground-glass-and-meat isn’t Mexican food!”
“It is too!” said Feghoot. . . . “It’s silicon carne.”
(Copyright © 1957 by Mercury Press. First published in THE MAGAZINE OF FANTASY & SCIENCE FICTION, 1957.)