If you use frozen raspberries, you will not need to mash them once cooked in syrup.
Mashing the berries is easier with a potato masher. If you don't have one, you can use a muddler or a fork. Just be sure to mash them before adding to the sugar water and add any juice that might come out.
Leave the raspberries in the syrup while it cools. Strain out the berries after it has cooled completely. This will intensify the raspberry flavors.
Keep the tea sealed in an air tight container in the refrigerator for up to 4 days. You may need to stit before serving and garnishing.
If you prefer, you can substitute blackberries.
You can substitute maple syrup or agave for the sugar in the syrup.