1. Combine sugar, grapefruit juice and zest, and water in a medium saucepan and bring to a simmer over medium-high heat. Reduce heat to medium-low and simmer, stirring occasionally, until syrup is slightly thickened, about 20 minutes. Remove from heat, add rosemary, and cool to room temperature, about 1 hour.
2. Strain into an airtight container (discard solids) and refrigerate for up to 1 month.
Source: Hannaford fresh Magazine, December 2019