Add all ingredients except the club soda into a shaker with ice and shake.
Strain into a highball glass over fresh ice.
Top with club soda.
Garnish with a pickled rhubarb stalk and lemon wheel.
*Rhubarb syrup: Add 2 qt water, 8 cups sugar and 4 cups roughly chopped rhubarb into a saucepan and cook over low heat, stirring until sugar dissolves. Cook for 5 minutes more, turn off heat and let cool. Strain and store in refrigerator for up to 1 month.
**Pickled rhubarb stalk: Toast 2 tbsp coriander and 3 tbsp pink peppercorns for 1-2 minutes in a saucepan over medium heat. Add 4 cups sugar and 1 qt raspberry vinegar, stirring until sugar dissolves. Chill mixture in refrigerator until cold and pour over 4 cups rhubarb, trimmed and chopped into 3-inch lengths. Refrigerate for at least a few hours before using.