Shake all the ingredients with ice and strain into a large goblet. Garnish with a mint sprig and orange slice.
This cocktail was named after Harry Dwoskin, who into his nineties would throw an elaborate birthday party for himself each year. Harry was fastidious with his money and claimed he had enough to cover the parties through his 104th birthday. I created this drink for his ninetieth at the Rainbow Room. He liked it so much that he served it at every birthday party until his last one at age ninety-six.