To make lilac syrup: Pick fresh lilacs and remove all stems. Cover with equal parts sugar and water, and heat gently (do not boil!) for a couple of hours - or heat it up, turn the burner off, and leave to infuse overnight. Strain. Add 1/3 c. lemon juice per 6 c. syrup to lower the pH for water-bath canning, if desired.
Mix the drink like a French 75.