Start by making the simple syrup: add water, sugar and lavender to a saucepan and bring to a boil. Once boiling, reduce to a simmer for one minute and then remove mixture from the heat.
Allow lavender to steep for approximately 30 minutes before pouring mixture through a fine mesh strainer.
To make the margarita: add ice and 2-3 tbsp* of the lavender syrup to a glass; add the tequila and lime juice, and then fill the glass up with sparkling water.