A variation on Michael McIlroy's "Rome with a View".
1 1/4 oz Cocchi Americano
1 oz fresh grapefruit juice
3/4 oz Fernet Branca
1/2 oz simple syrup (1:1)
Pinch of salt
1 1/2 oz soda water
Combine spirits, citrus and sugar
Double strain into iced highball with soda
Spread pinch of salt onto topmost ice.
Garnish with the oil of a grapefruit swath.
Fold the swath over the glass and serve.