Bring the water to a boil in a saucepan or tea kettle.
Meanwhile, use a mortar and pestle to bruise the rosemary a bit. This is optional, but allows the rosemary to release more flavor.
Combine the rosemary and mint in a tea strainer, and steep in the hot water for about 5 minutes. Pour into 2 teacups. Garnish with an orange or lemon slice if desired.
Notes
If you want a little caffeine in your tea, try steeping the above ingredients with a green or black tea bag.