In a saucepan combine chopped rhubarb, sugar and water, bring to a boil and cook over low heat for 7-10 minutes until rhubarb is very tender and falling apart.
Put the rhubarb syrup though a fine sieve and store in a clean, sterilised bottle in a refrigerator.
To make Rhubarb Moscow Mule
In a cocktail shaker combine vodka, rhubarb syrup and lime juice with ice cubes, shake.
Pour into two tall glasses filled with ice and top with ginger beer. Serve with limes wedges.