Add the fresh cranberries, water, and sugar to a medium saucepan and bring to a gentle boil over medium heat. Reduce slightly and cook for 8–10 minutes, stirring occasionally, until the cranberries burst fully and the liquid turns deep ruby red and aromatic. This step extracts acidity, color, and subtle tannic bitterness that define the drink’s structure.

Remove the saucepan from heat and immediately add the rosemary sprigs. Cover and let steep for about 10 minutes only. This short infusion provides clean herbal lift without pulling woody or pine-like notes. Over-steeping will dominate the drink and flatten the cranberry brightness.

Strain the syrup through a fine-mesh sieve into a bowl or jar, pressing gently on the solids to extract flavor without forcing pulp through. Stir in the pinch of fine sea salt while the syrup is still slightly warm, then allow it to cool completely. The finished syrup should taste sharp, lightly bitter, and balanced — not jammy or heavy.

In a large pitcher, combine 120 ml of the cooled cranberry rosemary syrup with the fresh orange juice. Stir gently to integrate. Taste the mixture — it should feel slightly too intense and structured at this stage since carbonation and ice will dilute it later.

Fill the pitcher generously with ice, pour in the chilled club soda, and stir once or twice only to combine. Pour into ice-filled glasses and garnish with fresh cranberries and rosemary sprigs. Serve immediately while the drink remains cold, crisp, and lively.