Prepare your tea. In a tall glass, steep an Earl Grey tea bag in 1/2 cup of boiling water for 15 minutes. This "tea concentrate" will flavour the whole beverage, so it needs to be strong! Once steeped, place the tea in the fridge or freezer to cool while you prepare the other components.
Make the vanilla simple syrup. In a small saucepan, combine the sugar and water. Bring to a simmer over medium-high heat, stirring to dissolve the sugar. When fully dissolved, take the syrup off the heat and stir in the vanilla extract. Let cool (Note 1).
Whip up some vanilla cold foam. Combine the milk and 1 to 2 tablespoons of Vanilla Simple Syrup in a microwave-safe glass. Heat for 20-30 seconds, until the milk is just warm (Note 2). Pour the milk into a french press and pump the handle until the milk is thick and foamy, about 15-20 seconds (See Note 3 for alternative foaming methods).
Put it together. Remove the glass of tea from the fridge or freezer and fill with ice cubes. Top with the vanilla cold foam and enjoy!