Complex sentence: The idea for the book came up when Nathan got a water controlled water bath for sous vide cooking in 2003, he tried to find information about this new cooking technique that had been invented in 1980's and that was used in many restaurants.
Split into simpler sentences: The idea for the book came up when Nathan got a water controlled water bath for sous vide cooking in 2003. He tried to find information about this new cooking technique that had been invented in 1980's and that was used in many restaurants.