Combine all the ingredients for the syrup in a small pot and bring to a boil. Stir to dissolve the sugar and boil for 1 minute. Remove from heat, strain, and let it cool.
Add all the ingredients for the lemonade into a big jug and stir to combine. Taste and add more syrup if you want it sweeter.
Serve with ice, lemon slices and mint leaves. Drink!
Instead of lavender, try this lemonade with rose geranium syrup! (omit lavender and add 4-5 leaves of rose geranium)