It contains stuff from the east, infused with a soy-based sauce (6)

'soy-based sauce' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.

'it contains stuff from the east infused with a' is the wordplay.
'contains' indicates putting letters inside.
'stuff' becomes 'ram' (ram can mean to stuff or push).
'from the east' says the letters should be written in reverse (on a map from right to left).
'infused with' is an insertion indicator.
'it' enclosing 'ram' is 'iramt'.
'iramt' reversed gives 'tmari'.
'tmari' going around 'a' is 'TAMARI'.

Can you help me to learn more?