Green-unripe damson recipe suggestions

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Do you have any suggestions?

The last few nights of torrential rain and wind has brought down much of my old damson tree. But these are stuffed full of green damsons, which unfortunately won't get the chance to ripe now (or will they?), so I'm wondering if I can still use them in a chutney/relish for a more earthy flavour or possibly try and emulate the Japanese pickled plums.

Any suggestions or recipe ideas?

[pg]