Angostura bitters are deeply cherished by fans of the Manhattan and other cocktails which require them. Angostura bitters are made by the House of Angostura in Trinidad and Tobago and the recipe is such a closely guarded secret that reportedly only five people in the world know it. In January 2010, the Washington Post reported that the world was facing Angostura bitters shortage, due to a dispute between the producer and bottler. While the shortage may be create difficulties for fans, there are a number of substitutes available.
Try switching to another brand of bitters which has a similar flavour. The Washington Post recommends Fee Brothers aromatic bitters as a viable substitute. Another suggested substitute is the Bitter Truth brand of bitters, which is made in Germany but available in some areas of the United States, as well as online.
If switching brands is not a viable option, you can also try making your own bitters.
Combine vanilla bean, lemon grass, star anise, juniper berry, clove, cardamom, anise and dried cherries in a small or medium mason jar with a lid.
Pour 1 cup of rye whiskey over the ingredients. Seal the jar and shake to blend.
Leave the ingredients to seep together for two weeks. Shake the jar every other day. After 14 days, strain through a fine-mesh sieve. Transfer to a bottle and store at room temperature.