Salt rim of a glass. Add all ingredients (except lime wheel) to a cocktail shaker with ice. Shake vigorously and strain into prepared glass. Garnish with a lime wheel and rhubarb ribbon.
Rhubarb Mint Syrup
Place the rhubarb and water in a saucepan over medium heat and bring to a low boil. Lower heat and simmer for 5 minutes or until the rhubarb is tender.
Puree in a food processor or using an immersion blender and strain through a fine strainer or cheesecloth, discarding solids. Return the rhubarb to the saucepan, along with the sugar. Simmer for about 5 minutes.
Remove from heat, drop in mint, and completely cool.
Strain and store in a glass container in the refrigerator until ready to use.