Drain the herring and cut into bite-sized pieces. Chop the pickles, onions, and apples into small pieces. Place everything in a bowl.
In a separate container, combine the sour cream portions. Stir in roughly 1/4 cup milk and season with pepper. Pour over the herring mixture and add the allspice grains and bay leaf.
Cover and refrigerate for 8 to 10 hours or overnight until flavors develop.