Place the lemon pieces in the bottom of a mixing glass along with the simple syrup and maraschino liqueur; muddle well. Fill a rocks glass with ice, and add that ice to the mixing glass along with the vodka. Shake well for 10 seconds, and then pour the entire contents of mixing glass back into the rocks glass, lemon pieces and all. Top with additional cracked ice.
Recipe by Audrey Saunders, a talented career bartender. 'OP' is an aquavit (flavored vodka) from Sweden flavored with peach, orange, ginger, and other spices.