Lots of lovely raspberry bushes out now, if the mosquitos will let you get to them! Here’s something to try
http://hungerandthirstforlife.blogspot.com/2013/01/fermented-raspberry-leaf-tea_26.html
This technique was suggested to us by Diana Pusko who has a Mexican restaurant on Nida, and was kind enough to take us on a foraging walk in the forest. She says to rub the leaves then put them in a jar for 24hrs. After this short fermentation, lay them out to dry fully before jarring them. Then just make a tea with the leaves, add sugar and wait for the microorganisms to get busy.
We’ve tried with one tea made from a hot infusion and another from a cold one.