Clean the oysters and then put them in a saucepan with the apple cider, bringing to a boil. Steam oysters, covered, over a fairly high heat until they begin to open for four minutes. Transfer to a plate after oysters have opened, keeping the liquid and throw away the unopened oysters. Chill oysters until cool.
Pour the oyster liquid through a paper towel-lined sieve into a bowl to remove any grit. Stir two tablespoons of strained liquid together with remaining ingredients and add salt to taste.
Remove flat half of oyster shell and loosen oyster with a sharp knife. Place oysters in rounded half of shell. Arrange on plates and spoon sauce over oysters.
