Line a cookie sheet with paper towels, set aside. Whisk the egg and water together in a mixing bowl. Add flour, salt, baking powder and whisk thoroughly for 2 to 3 minutes or until smooth, scraping sides of bowl.
On a slice of bread, arrange 2 slices of ham, turkey, and cheese, covering the bread evenly. Place another slice of bread on top and slice each sandwich in half diagonally.
Heat oil between 365 and 375 degrees fahrenheit in a 10 inch pan. Do not let oil reach a higher temperature than this; if it starts to smoke, turn it down. Dip half of the sandwich into the batter, allowing the excess to drain, and very carefully place into the oil. Repeat with other sandwich half. Cook 3 minutes on each side or until golden brown. Place the cooked sandwich on the prepared cookie sheet in a warm oven until ready to serve. Repeat with the other three sandwiches.
Cook one time and allow the oil to reach the desired temperature between each. Sprinkl with confectioners sugar and shave with blackberry preserves on the side.