Add all the ingredients into a shaker and dry-shake (no ice).
Add ice and shake again.
Add the soda water to top.
Strain into a Highball glass over fresh ice.
Garnish with a dusting of sumac powder.
*Turmeric simple syrup: In a blender, add 10 oz water and 4 oz fresh turmeric root. Blend on high for 30 seconds. Transfer mixture to a saucepan. Bring to a simmer over medium heat, then add 4 oz sugar. Cook for 5 minutes. Strain through a fine-mesh sieve or cheesecloth.