Gin cocktail

Cooper looks at me with dismay as I try out a new cocktail - tarragon & grapefruit G&T.
I still have a glut of fresh tarragon which I want to use up inventively. I've made flavoured butter, infused oils & vinegar, made fresh bread, cheesy biscuits and dried some but open to any suggestions.
The cocktail was lovely - 2 parts gin, 2 parts grapefruit juice, 2 sprigs tarragon, 1 tbsp soft brown sugar & 2 parts tonic.