Juniper berries are available in well-stocked spice sections of supermarkets.
- Portion size 5 servings
Plunge onions into pot of boiling water for 1 minute; drain. Peel and trim; combine in large bowl with salt and cover with water. Let stand for 8 hours or overnight. Drain; rinse in cold water and drain well.
In large heavy saucepan, bring to boil vinegar, sugar, juniper berries, cinnamon, cloves and peppercorns. Remove from heat; cover and let stand for at least 30 minutes or up to 2 hours. Strain out spices and discard.
Bring vinegar mixture back to boil. Place tarragon sprig in each of three 2-cup (500 mL) sterilized canning jars. Pack jars with onions; pour in vinegar mixture, leaving 1/4-inch (5 mm) headspace. Seal jars; process in boiling water bath for 10 minutes.