Stir liquid ingredients with ice; pour into Old Fashioned glass with big cubes. Express and drop lemon in to garnish.
The tangelo liqueur is a local brand (Schapp Dragon Distillery). Curaçao or other citrus liqueurs (eg mandarin) work as a sub, but then the initials won't spell JRRT.
Inspired by a preview of The Desolation of Smaug. The drink could be Hobbit-forming.