This might be what I hin mind.
https://ediblewesternny.ediblecommunities.com/recipes/quick-apple-or-pear-shrub
" Gastrique Uses
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Put your shrub in a saucepan over low heat and reduce it until it coats the back of your spoon.
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Remove from heat.
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Drizzle over a peach crumble or enjoy it over vanilla ice cream. This gastrique should last for many months in your fridge, if you can save it that long!
Yield 1½–2 cups syrup"
Or
https://www.zingermansdeli.com/2012/07/vinegar-not-just-for-vinaigrettes/