Add the raspberies to a large glass container and use a muddler to gently muddle them to release some of the raspberry juice.
Next, add the orange slices, black tea, mint leaves, and agave to the glass container. Pour in the 6 cups of water so that 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 pink/red 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 raspberries, and a slice of orange. Enjoy!