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 can't tell whether this works.

'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' is a reversal indicator (on a map from right to left).
'infused with' indicates putting letters inside.
'it' going around 'ram' is 'iramt'.
'iramt' in reverse letter order is 'tmari'.
'tmari' enclosing 'a' is 'TAMARI'.

Can you help me to learn more?