Preparation Remove a 4-by 1-inch strip of zest from 1 tangerine with a sharp vegetable peeler (preferably Y-shaped), then scrape off any white pith from strip. Squeeze 1/3 cup juice from tangerines. Bring juice, zest strip, and remaining ingredients to a boil in a heavy medium saucepan, stirring until sugar has dissolved, then simmer, uncovered, until berries have burst, 15 to 20 minutes. Remove from heat and cool completely. Discard zest before serving if desired. Cooks' note:Conserve can be made 2 days ahead and chilled.