To prepare the blueberry puree, simmer the blueberries and water in a saucepan over medium heat for 5 minutes or until broken down. Mash the mixture or blend in a blender and allow to cool.
Slice the lemon in half and slice off two slices for decoration.
Roughly chop the mint.
Add the mint, blueberry puree, lavender syrup, gin and a squeeze of lemon juice to the bottom of each glass. Mix well with a spoon.
Add ice to each glass and then top up with soda water. Mix to stir up the blueberry mixture at the bottom.
Serve with a slice of lemon and some more mint.