Muddle the raspberries and sugar. Place the raspberries and caster sugar in a large, heavy-based saucepan. Use a potato masher or the back of a wooden spoon to gently crush them together until the berries break down and the sugar starts to dissolve. You should see a bright pink-red liquid pooling in the bottom of the pan, and the smell will be sharp and sweet all at once.

Add the water and bring to a simmer. Pour in the cold water and stir everything together. Set the pan over a medium heat and bring it to a gentle simmer — you’ll see small bubbles rising to the surface, and the liquid will deepen into a rich ruby colour. Let it bubble softly for five minutes, stirring now and then, until the raspberries have mostly fallen apart and the liquid is fragrant.

Steep the tea bags. Remove the pan from the heat and drop in the tea bags, pushing them down into the hot raspberry liquid. Let them steep for exactly four minutes — any longer and the tea will turn bitter. The colour will shift to a deeper, almost mahogany red, and you’ll smell both the floral tea and the fruit together.

Strain the mixture. Set a fine-mesh sieve over a large heatproof jug or bowl. Pour the raspberry tea through the sieve, pressing gently on the solids with the back of a spoon to extract every last drop of juice. Discard the pulp and tea bags. You’ll be left with a clear, jewel-toned liquid that smells intensely of raspberries.

Add the lemon juice and sweeten to taste. Stir in the lemon juice, then taste the warm tea. If you’d like it sweeter, add a little more sugar or a drizzle of honey while the liquid is still warm, so it dissolves easily. The lemon brightens everything and balances the sweetness with a little tang.

Chill completely. Allow the tea to cool to room temperature on the counter, then transfer it to the fridge to chill for at least one hour. You’ll know it’s ready when it’s cold to the touch and the flavours have had time to meld together into a smooth, rounded taste.

Serve over ice. Fill tall glasses with plenty of ice cubes. Pour the chilled raspberry tea over the top, dividing it evenly. Garnish each glass with a sprig of mint, a few fresh raspberries, and a thin slice of lemon. The mint will release its scent as you lift the glass, and the first sip should be refreshing, fruity, and not too sweet.