Series on sentimentality found in lunch box (6,6)

I believe the answer is:

string cheese

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'lunch box' is the definition.
The definition and answer can be both things that one consumes for nourishment as well as being singular nouns.
Maybe there's a link between them I don't understand?

'series on sentimentality' is the wordplay.
'series' becomes 'string' (sequence of similar items or events).
'on sentimentality' becomes 'cheese' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'string'+'cheese'='STRING CHEESE'

'found in' acts as a link.

Can you help me to learn more?

I've seen this clue in The Daily Express.

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