Rub the edge of each coupe glass with lemon before gently rolling the edge in sugar, if desired.
Chill the glasses in the fridge for 15 minutes.
While the glasses are chilling, place a cup of ice in a cocktail shaker.
Add cognac, triple sec, and lemon juice.
Shake vigorously for 10 to 20 seconds and pour it in the chilled coupes or martini glasses. Garnish with a lemon or orange twist if desired.
Notes
If you like the contrast of sweetness, add a sugar rim to your coupe glass. If you don't have fine sugar, simply blend the sugar in a food processor.
Be careful not to get sugar inside the glass, keep it on the outside only. Use a damp cloth to remove any sugar that falls in the glass, and to level the edge of the sugar on the glass to approximately ¼-inch to ½-inch.