Steep 1 teaspoon lapsang souchong tea (or 1 teabag) in 1 cup boiling water in a mug, small teapot, or measuring cup. Transfer the mixture to the fridge to chill. Once the mixture is cooled, strain out the tea leaves or remove the bag. Stir in 1/4 teaspoon vanilla extract. This is your "non-alcoholic whisky".
Add ¼ cup of the lapsang souchong ("non-alcoholic whisky") mixture, 1 ounce lemon juice, 1 ounce simple syrup , and 1 Tablespoon aquafaba to a cocktail shaker without ice. Shake vigorously for about 10 seconds. Fill the shaker about halfway full with ice, and shake vigorously again, until the outside of the shaker is very cold, about 10-15 seconds longer.
Strain the cocktail into a coupe or rocks glass, and garnish as desired with a slice or wedge of lemon.
Notes
To make simple syrup, simply dissolve 1 cup granulated sugar in 1 cup hot water. Make sure the syrup is fully cooled before using. Store any leftovers in a small jar or bottle in the fridge.Aquafaba is the water from canned chickpeas, or the water that chickpeas was boiled in. It creates the foam that is often seen on cocktails that contain egg whites, without the risk of salmonella. It is optional - feel free to skip it if you don't have any, but your cocktail will be without foam and have a slightly thinner mouthfeel.