Put the tea bags and half the mint into a large jug, then pour over 1.2 litres boiling water from the kettle. Leave to infuse for 10 mins, then remove the bags and stir in the sugar. Once cool, remove the mint, add the orange juice, lemon juice and Pimm’s, and chill thoroughly. Can be made up to a day ahead.
Serve over plenty of ice, with slices of orange, lemon and strawberry, and remaining mint sprigs.