Start by slicing the peaches into wedges (discarding the pit) and thinly slicing the lemon.
Add the peach to a large glass container and use a muddler to gently muddle them to release some of the peach juice.
Next, add the lemon slices, black tea, mint leaves, and agave to the glass container. Pour the 6 cups of water in so it covers all the mix-ins.
Stir everything together, then cover the container.
Store the tea in the fridge for 10-24 hours. It will go from a clear color to a orange/yellow color during this time.
After steeping, remove the tea from the fridge and stain out all of the mix-ins.
Serve the tea as is or in a glass with ice, fresh peach slices, and a sprig of mint on top. Enjoy!