Pour about 5 inches oil into a deep fryer or large cooking pot. Heat oil to 365°F.
While oil is heating, in a medium bowl, whisk together egg and water.
In another separate bowl, add flour, baking powder, salt and pepper, to taste. Mix well.
Gradually add dry ingredients into the egg mixture, whisking constantly, until smooth.
Place the batter in the refrigerator to chill while assembling the sandwiches.
Place 4 slices bread on a work surface.
Layer 2 slices turkey on each bread slice.
Add 2 slices Swiss cheese and 2 slices ham on another to each sandwich (Cheese should be between the ham and turkey).
Place remaining 4 slices of bread atop the sandwiches.
Cut each sandwich into quarters and secure with toothpicks.
Dip each sandwich quarter into prepared and chilled batter, coating all sides evenly.
Carefully place the sandwich quarters into the hot oil, a few at a time, and fry until golden brown on all sides.
When browned, remove sandwich quarters to a paper towel-covered plate to drain. Remove the toothpicks and set aside and keep warm.
Arrange the sandwich quarters on a serving tray or individual serving plates, 4 to a plate, and dust with confectioners’ sugar just before serving.
Serve with raspberry preserves on the side for dipping.