Elderflower cordial, a liqueur derived from the European alpine botanical, adds a contemporary twist to the classic Collins in this recipe. Start with two ounces of Juniper Green London Dry Gin in a Collins glass. Add 0.5 ounces of an elderflower cordial, such as St-Germain Liqueur, one ounce of lemon juice, and a splash of simple syrup or gomme. Stir. Top with soda and a lemon garnish.