Steep the Earl Grey tea bags in hot water for 5 minutes, then remove the bags.
Stir in honey and vanilla extract, then let the tea cool completely.
In a glass, muddle fresh blackberries and lemon juice until well combined.
Fill the glass with ice cubes, then pour in the cooled tea.
Top with sparkling water and stir gently.
Garnish with blackberries and lemon slices before serving.