Combine all the ingredients in a small food processor or clean coffee grinder and blend until the hibiscus flowers are very small pieces. Keep in an air tight container.
Combine the cocktail ingredients to a cocktail shaker and add ice. Fill a large rocks glass with pebble ice. Shake the cocktail well then strain into the prepared rocks glass. Garnish with a hefty pinch of the Hibiscus chili seasoning and two thin mango slices.
Notes
* Rich simple syrup is a 2:1 ratio of sugar to water. Heat on a stove until sugar is dissolved. Keep in an airtight container in refrigerator. Should last about 2 weeks. ** You can find dried hibiscus flowers in seasoning sections of well stocked grocery stores, international stores or in bulk sections of Mexican grocery stores. Make sure they are dried and not just dehydrated where they are still chewy. You want the dried kind so they crumble when blended.