Combine first 9 ingredients in a bowl. Cover and chill 1 hour.
Preheat broiler.
Gently loosen lobster meat from top inside of shells.
Cut lengthwise through top of shells using kitchen shears; press shells open. Starting at cut end of tails, carefully loosen meat from bottom of shells; keep meat attached at end of tails. Lift meat through top shell opening; place on top of shells.
Place lobster tails on a rack in a shallow roasting pan.
Combine vinegar, water, oil, and tarragon; brush lobster with half of vinegar mixture. Broil 10 minutes or until lobster flesh turns opaque; baste with remaining vinegar mixture after 5 minutes.