Rosemary Agrodolce

Combine honey, rosemary, and 2 Tbsp. water in a small saucepan over medium heat; season with salt. Bring to a simmer, stirring to dissolve honey, then cook, swirling pan occasionally, until slightly thickened and fragrant, about 2 minutes. Stir in vinegar and cook 1 minute to evaporate some of the vinegar. Remove from heat and stir in onion. Let cool in pan.

Do ahead: Agrodolce can be made 1 week ahead. Let cool, then cover and chill. Bring to room temperature and stir to combine before using.