Freeze the bread slices for a few minutes until firm. This will give you clean edges on the tea sandwich.
If making round tea sandwiches, use a 2 to 2½ inch round biscuit or cookie cutter and cut 24 circles from the bread. If making triangular tea sandwiches, you will trim the crusts after assembling the sandwiches.
Using a sharp knife, cut the apple in half vertically. Then, slice the apples as thinly as possible and remove the core and seeds. A mandolin works great on the thinnest setting.
Cut 12 slices of herbed goat cheese and cut 12 circles from the cheese slices using a round cutter.
Make the spread
Combine the mayonnaise, horseradish, salt, and pepper until well combined. Set aside.
Assemble the sandwiches
Spread 1-2 teaspoons of the spread onto each frozen bread slice. Top with Swiss cheese, folded or sliced turkey meat, goat cheese and finally apple slices. Top with another bread slice. If making triangular sandwiches, use a serrated knife in a gentle sawing motion, trim the crusts and then cut diagnolly into 4 sandwiches each.
Serve immediately or cover with a damp paper towel and place in an airtight container and refrigerate until ready to serve.