Help me make capers from eldertree flowerbuds...

Some time ago, I watched a TV program where a young chef sourced elderflowers, still all green and closed flowerbuds.

He preserves them in a vinegar solution and uses them as elderflower capers. I have to try this!

Does anyone make preserves in vinegar of some sort to give me good advise on how to do this?

 

These new young chefs are not only highly trained, they have this urge to do research on their own recipes that will open very new resources. This guy is one of them, earned a Michelinstar before his 30th birthday. Does a lot of sourcing in the fields and woods around his place looking for wild herbs! Has his own restaurant not so far from where I live. Here's his website; http://www.indewulf.be/en/kitchen/philosophy/

I need to add that I was very intrigued when I saw him use "eldercapers", since I infuse one of my own homemade vinegar infusions with elderflowers -opened this time, no buds- and make my own jam from the berries. The capers would be a nice addition.