In mixing glass or shaker filled with ice, combine Cointreau, brandy, and lemon juice, and shake vigorously. Wet rim of a 3- to 4-ounce cocktail glass and place on a lightly sugared plate. Strain liquor into the glass and serve.
In order to avoid your having to scale back the lemon juice, we've provided a recipe for a smaller drink, which is close to the original Sidecar.