1. In a medium saucepan over high heat, bring water and stevia to a boil. Turn off heat, add tea bags, and steep for 5 minutes, stirring occasionally. Remove tea bags and add berries to the pot. Steep for 5 minutes.
2. In a blender, add brewed tea with berries and lemon juice, and process until smooth. Strain through a fine mesh strainer into a serving pitcher. Stir in vodka if using. Place in the refrigerator to cool. Pour into glasses filled with crushed ice. Garnish with fresh berries or lemon slices if desired.