Start by chilling your martini glasses in the freezer so they stay icy cold when serving.
Pour a small amount of sanding sugar onto a shallow plate and lightly moisten the rims of each glass with a lemon wedge before gently dipping them into the sugar to coat evenly.
Fill your cocktail shaker halfway with ice cubes, then pour in the green apple liqueur, green apple syrup, and lemon juice.
Add a few drops of green food coloring into the shaker to deepen the vibrant green hue of the cocktail.
Secure the lid on the shaker and shake vigorously for about 15-20 seconds until the mixture is well chilled and slightly frothy.
Strain the mixture through a strainer into the prepared, chilled martini glasses to achieve a smooth, pulp-free presentation.
Garnish with a thin slice of green apple or a skewered cherry if desired for a spooky finishing touch.
Serve immediately and enjoy this vividly haunting, tart cocktail that’s perfect for Halloween parties.