Agave vanilla simple syrup: Place water and agave in a small saucepan. Slice vanilla pod lengthwise and scrape seeds with a spoon and add to saucepan along with the pod. Heat gently for 5-10 minutes, then let cool and discard pod.
For the cocktail: Let hibiscus flowers steep in boiling water for five minutes, then strain out flowers and allow liquid to cool. Add hibiscus tea to an ice-filled cocktail shaker, along with the agave vanilla syrup, tequila and lime and shake well. Strain into an ice-filled glass (we used an ice sphere) and garnish with a lime wheel.