To make lavender syrup: simmer 1/2 cup water with 1/2 cup sugar and 1 tbsp dried culinary lavender, stirring until sugar dissolves. Remove from heat, steep for 15 minutes, strain, and cool.
I use culinary lavender, as other types may taste bitter.
Fresh grapefruit juice works best, but bottled can be used if needed.
Gin brings out the herbal notes, while vodka makes the drink softer.
For less sweetness, use less syrup. Adjust to your taste.
Always strain the lavender syrup well to prevent bits in the cocktail.