Pack vegetables into 2 clean 1-quart glass jars. In another jar, combine the salt, sugar, mustard seeds, sliced shallots, vinegar and white wine and shake until the salt and sugar dissolve. Add 1 cup of water and pour the brine over the vegetables. Tuck the tarragon sprigs between the vegetables. Add enough water to cover the vegetables and keep them submerged. Close the jars and refrigerate overnight or for up to 1 month.