How to Make It
Place the dried lavender buds in a small heatproof bowl. Pour the boiling water over the top and let steep for 30 minutes. Strain the lavender infusion through a fine sieve set over a small bowl; discard the solids. Cover and refrigerate until cold.
In a rocks glass, stir the tonic with the gin, lime juice, agave and 1/2 ounce of the lavender infusion. Fill the glass with ice, garnish with the lime wedge and lavender sprig and serve. Use the remaining lavender infusion to make more cocktails.