Heat in the pan for about 10 minutes. You want it to be just under boiling.
Once heated, blitz with a hand blender, or in an actual blender.
Once blitzed, pass the mixture through a sieve and discard the lumpy mush.
Let the mixture cool completely.
To Serve the Raspberry Lemonade
Pour the concentrate into a jug/glass and add more water. You want the ratio to be 1/3 concentrate, to 2/3 extra water. Or if you prefer it a bit weaker, obviously add more water in comparison to concentrate!
You can use still water, or sparkling water, but you don't need to use lemonade as the flavour is already in the concentrate.
In each glass, or in your jug, add some fresh raspberries, lemon slices, and ice, and serve!
Notes
This recipe is made as a concentrate at first, because then you can adjust to your preferred strength.
If you prefer it sweeter, you can add more sugar into the original mixture.
You can also make less if you prefer, but this makes about 500ml worth of concentrate!
I used fresh raspberries, but I'm sure frozen raspberries would work well!
The mixture needs to be stored in the fridge, and will last for 4-5 days if covered. Best served on the day of making.
If the mixture or drink sits for a bit, it might settle so will need a stir.