The day before, rinse the plums under cold water and pat dry with a clean cloth. Halve them lengthwise and remove the pits.
Combine the plums, lemon juice, and sugar in a bowl. Let macerate for 1 hour.
Warm the Pinot Noir with the honey. Add the peppercorns, cinnamon, star anise, and orange zest. Bring to a boil and simmer for 5 minutes. Remove from heat, then add the macerated plums to the syrup. Allow to cool completely.
Drain the plums. Line a loaf tin with plastic wrap. Arrange gingerbread slices on the bottom. Layer with poached plums, then a layer of slightly softened vanilla ice cream, more plums, and finish with gingerbread.
Freeze overnight.
Strain the spice syrup and reduce over low heat for 20 minutes.
Unmold the terrine 30 minutes before serving, slice, and glaze with the reduced syrup.
