This Raspberry cordial concentrate is a modified version found on a number of internet cookery pages, and it hails originally from The Anne of Green Gables Cookbook by Kate MacDonald.
In a saucepan add sugar to raspberries and cook until soft and the sugar is dissolved. Add the strained juice of 2 lemons.
Strain through cheesecloth in a sieve.
The mix will need plenty of dilution for drinking but can be stored frozen in its current state (put it in a small, sealed freezer container) and thawed as needed.
Usually this amount of concentrate will need 4 cups or more of water added to it, and some people prefer it more dilute than that. Experiment with the amount of sugar – you may be able to gradually reduce it further without anyone noticing!
If you have lots of raspberries available, make a double batch, because in this concentrated form it will keep for months in the freezer.