You start with 1/2 inch filets not canned tuna fish

Answer:
For centuries fishermen in warm climates have turned to drying or curing fish to preserve their catch. The fishermen off the southwest coast of Spain would pack fish in sea salt, and then hang them in the sun to dry. Even though it is not necessary to preserve fish this way with today’s advances in refrigeration and on-board freezers, people still love to eat salted fish. Dried tuna or mojama as it is called in Spanish is considered a delicacy and is produced in the provinces of Huelva and Cadiz in the Atlantic, as well as Valencia, Murcia and Almeria in the Mediterranean. The tradition of drying tuna in Spain goes back many centuries and it is known that the Arabs dried tuna during their reign, calling it musama.
As the tuna dries, it shrinks. The pale red fish turns a dark reddish-brown and has a firm consistency. You can buy mojama in markets all over Spain. It is sold in chunks by weight. If you do not live in Spain, you can purchase it in vacuum-packed packages at gourmet or ethnic food markets, or over the internet.
Mojama makes a superb and simple tapa served with sliced bread and toasted almonds or green