Triple sec sour

I derived this recipe from Cointreau's own suggested cocktails on their website. Although theoretically any orange liqueur can be used for this drink, keep in mind that Cointreau is less sweet than other orange liqueurs, and so using triple sec or orange curaçao may require a higher proportion of lemon juice. Below is an excerpt from their own statement about the cocktail:

"A modern take on the Sour category, mixing Cointreau as a base and getting a refreshing and fruity drink, well suited for summer parties. Made with Cointreau L'Unique, Fresh Lemon Juice, Fresh Orange Juice, Egg White, it is shaken to perfection and served in a lowball with orange twist for the finishing touch. A expert-level strong cocktail, it is perfect for aperitif and best enjoyed summer. Discover the full range of classics recipes and find your perfect Cointreau cocktail." (from https://www.cointreau.com/int/en/cocktails/cointreau-sour)