Add Sugar Cube: Place 1 sugar cube in your Julep cup or Old Fashioned glass.
Add Angostura bitters: Pour 5 dashes Angostura aromatic bitters over the sugar cube.
Add Soda Water: Measure and pour 1 dash soda water on the sugar cube as well.
Muddle: Muddle the sugar cube to reduce it to powder and make sure it will fully dissolve later on.
Add Mint: Place 6-8 fresh mint leaves in one hand and gently smack it with the other, to release its aromas. Add the mint to the Julep cup or Old Fashioned glass.
Add Gin: Measure and pour 2 oz London Dry Gin of your choice into the glass.
Add Ice: Fill the glass three-quarters full with crushed ice.
Stir: Using a bar spoon or long stirrer, churn well to combine the ingredients, until the cup is frosty.
Add Ice: Add a straw and top up with more crushed ice.
Garnish: Place a mint sprig into the glass and sprinkle some icing sugar on top for garnish. Serve immediately.