- 2 pounds red onions, thinly sliced, separated into rings
- 6 4-inch fresh rosemary sprigs
- 2 cups Champagne vinegar or white wine vinegar
- 1 heaping tablespoon mixed pickling spice
- 2 teaspoons coarse kosher salt
Place 1/3 of onions in large (at least 2-quart) jar with tight-fitting lid. Add 2 rosemary sprigs. Repeat layering twice more with remaining onions and rosemary.
Bring vinegar, 1 1/2 cups water, sugar, pickling spice, and salt to boil in medium saucepan over high heat, stirring until sugar dissolves. Reduce heat and simmer 2 minutes, stirring often. Pour hot liquid over onions, pushing onions down into liquid. If necessary, add just enough cold water to cover onions. Cool. Place lid on jar; refrigerate at least 1 day. DO AHEAD Can be made 2 weeks ahead; keep chilled.