From Palazzino Mraz
Garnish: lime wheel
Combine all ingredients in a cocktail shaker with ice and shake hard 5-7 times to break up the ice just a bit.
Pour into a rocks glass and garnish with a lime wedge or wheel.
Stick with Cointreau for the orange liqueur. I once made this with Grand Marnier instead and regretted it. Regular triple sec is likewise not as good.