Oysters with apple mignonette

Active time: 35 min. Start to finish: 40 min.
6 medium oysters such as Blue Point or Belon
1/2 cup apple cider or juice
3 tablespoons finely chopped tart apple
2 tablespoons finely chopped red bell pepper
1 tablespoon finely chopped shallot
1 tablespoon finely chopped fresh flat-leaf parsley
1 tablespoon cider vinegar
1/4 teaspoon coarsely ground black pepper

Scrub oysters well. Combine oysters and apple cider in a 2-qt. saucepan and bring to a boil. Steam oysters, covered, over moderately high heat until they just open, checking occasionally after 3 minutes and transferring to a plate as they open. (Reserve steaming liquid and discard any unopened oysters.) Chill oysters, loosely covered, until cool, about 30 minutes.

While oysters are chilling, pour oyster steaming liquid through a paper towel–lined sieve into a bowl to remove any grit. Stir 2 tablespoons strained liquid together with remaining ingredients and salt to taste. Discard remaining strained liquid.

Remove flat half of oyster shell and loosen oyster with a sharp knife. Put oysters in rounded half of shell. Arrange on plates and spoon sauce over oysters.