We learned of the 'regal shake' during a March 2015 bar hopping adventure in San Diego--at Noble Experiment, to be exact. Theo Lieberman of Lantern's Keep and Milk & Honey introduced this technique of shaking with a grapefruit peel. This is our effort.
1 oz Aperol
1 oz Rye Whiskey
1 oz Cynar
1 Grapefruit Peel
Shake with ice and strain into a chilled cocktail glass. No garnish.