In a medium size saucepan add the raspberries, sugar and 1 cup water, bring the liquid to a boil, lower the heat and leave to simmer for 15 minutes. Drain the syrup from the pulp and keep it aside.
In a large jug, add two cups of boiling water and steep 4-6 teabags for 10 minutes. Remove the tea bags and add 3 cups of ice, lemon juice, cold water and raspberry syrup to your taste. Add lemon slices and fresh mint and serve.