Make the simple syrup:
Combine water and sugar in a saucepan set on medium heat. Stir well to dissolve sugar. Add crushed cardamom seeds and bring to a boil. Remove from heat and allow to steep for 30 minutes. Strain the juices, removing pulp, into a clean (sterile) Mason jar. Strain cooled simple syrup into the jar, discarding cardamom seeds. Shake well before using. Cap and refrigerate after use. Keeps for months. Makes 16 ounces.
Cocktail:
Stir and serve on the rocks.
