The origins of chashu pork can be traced back to China, where it is known as Char Siu. The technique of roasting or braising pork and flavoring it with a sweet and savory sauce has been a part of Chinese cuisine for centuries. Chinese immigrants brought their culinary traditions to Japan, including the concept of Char Siu. The term "Chashu" is derived from the Cantonese term "Char Siu," which translates to "fork roast" or "fork burn" in English. This refers to the traditional method of cooking the pork by skewering it on long forks and roasting it over an open fire or in a special oven. The exact origins of Chashu pork are unclear, but it is believed to have originated in southern China, particularly in the Guangdong province. It has been a staple in Cantonese cuisine for centuries, with its roots dating back to ancient cooking methods and preservation techniques.
This step is optional, not applicable if you go from frozen.
Later on I will also include pressure cooking method here.