For the Chelsea Sidecar recipe we use a martini glass. Fill the martini glass with ice. Let it stand for 2 minutes to cool it down. Empty the glass out and rub the rim with the lemon peel. Fill a cocktail shaker with ice and add the gin, the triple sec and the lemon juice and shake vigorously. Strain the mixture into the chilled martini glass. Garnish your Chelsea Sidecar cocktail with the lemon twist and voila.