Make the mignonette: In a medium bowl, stir together the vinegar, shallot, cranberries, honey, sea salt, and pepper. Taste and adjust
the seasoning, keeping in mind that you want mouth-puckering tartness.
Serve over fresh oysters arranged on a bed of crushed ice and rock salt to keep them cold and fresh.
MAKE AHEAD The mignonette can be prepared up to three days in advance.