My new best friend (among cocktails)

I'm making this one at home a lot these days: the SIDECAR. Traditional recipes use brandy and cointreau, but I take it up a notch and substitute cognac and Grand Marnier. Either way, it's a delectable treat while cooking dinner, or just sitting on my front porch listening to the birdies sing.

SIDECAR (makes one cocktail; can be doubled):
Fill a quarter-cup measure about two-thirds full with the brandy or cognac. Fill it up with cointreau or Grand Marnier.
Pour this into a cocktail shaker with ice.
Add the juice of 1/.2 large lemon and ounces of simple syrup.
Shake well and strain into a glass filled with fresh ice.
Garnish with a slice of fresh orange.