for the hibiscus-cardamom-fennel syrup
4 tbsp dried hibiscus flowers, petals
5 cardamom pods (green), whole
1 tsp fennel seeds, whole
½ cup water
½ cup white sugar
for the cocktail
1¾ oz gin
½ oz yellow chartreuse
½ oz hibiscus-cardamom-fennel syrup
¾ oz lime juice
¾ oz egg white (fresh)