To a large saucepan, add the water and sugar. Heat and stir until the sugar is dissolved.
Remove from the heat and stir in the lavender. Let 'steep' (leave all in the pot) until cool.
Strain this mixture through a fine mesh sieve over a bowl. Add the vanilla to the contents of the bowl (our syrup) and stir to combine. Pour this syrup into a mason jar or similar storage container. Keep in the refrigerator for up to 3 weeks.