For the apple tea:
1) In a medium saucepan, bring the water to a boil over high heat. Remove the pan from the heat and stir in the tea bags. Allow the liquid to cool to room temperature, about 1 hour.
2) Remove the tea bags and discard. Add the vanilla simple syrup and stir. Pour the mixture into a glass pitcher. Add the apple and lemon slices and refrigerate for 1 hour.
3) Pour the tea into ice-filled glasses and serve.
For the vanilla simple syrup:
1) In a small saucepan over medium heat, combine the sugar, water, vanilla bean, and vanilla bean seeds. Bring to a boil, reduce heat, and simmer for 5 minutes, stirring occasionally, until the sugar has dissolved. Remove the pan from the heat and allow the syrup to cool, about 20 minutes. Strain before using.