In a small bowl, stir together sauerkraut and caraway seed.
In a medium bowl, whisk together mayonnaise, mustard, Worcestershire sauce, horseradish, and sugar until blended to make an aïoli. Spread a layer of aïoli onto 6 bread slices. On aïoli side of 3 bread slices, evenly layer rocket, corned beef, and sauerkraut. Top each with a remaining bread slice, aïoli side down, to make 3 whole sandwiches.
Using a serrated bread knife in a gentle sawing motion, trim and discard crusts from sandwiches. Cut each sandwich into 4 rectangular tea sandwiches. Serve immediately, or cover with damp paper towels, place in a covered container, and refrigerate for up to an hour.
Recipe by TeaTime Magazine at https://teatimemagazine.com/corned-beef-cabbage-tea-sandwiches-recipe/