From Japan, the Sancho is one of the false ‘flag peppers’, in that botanically it is not a pepper at all, but part of the citrus family. It is similar to the Sichuan pepper in its appearance, and in its flavour profile (although it is milder) – fruity and sharp with a slightly numbing heat.
Generally sold ground, these whole berries stay fresher and sharper. They can be ground in a mortar & pestle for seasoning purposes.
In Japan, sancho is traditionally used to season grilled eels, and it is also one of the seven main spices used in sashimi mix. Also it is a main ingredient in teriyaki, and can be used with or instead of red chilli in many more dishes.
It is wonderful too used as a part of your own peppercorn mix for general use, giving the mix a distinctly fruity and exotic edge. A very versatile spice!