This is not fixed. Originally, Sanxian soup was not originally available in Sichuan cuisine. The three raw materials of Sanxian can be changed. Pig viscera, pork, muscle or fungi are commonly used in Sichuan cuisine. Let me recommend one for you, so I won't tell you about the pig viscera, because it smells bad after being processed, such as pork tenderloin, ham and Pleurotus eryngii.