- To make the Angostura syrup, combine 1 part Angostura bitters, 1 part water and 2 parts sugar in a pot.
- Place the pot on the stove and bring the mixture up to simmer.
- Remove from heat and let rest for 20 minutes.
- To make the cocktail, pour Angostura syrup along with other ingredients into shaker and shake with ice.
- Strain into glass with ice and garnish with orange zest.