Sift flour, salt, and baking powder together. Add water to beaten egg, then add to flour mixture and mix well. Set aside.
Make a sandwich using first turkey, then Swiss cheese, and then ham. Cut sandwich into quarters using toothpicks to hold sandwich together. Dip sandwich in egg batter and fry in 360°F oil until golden brown.
Remove toothpicks and sprinkle with powdered sugar. Serve with raspberry jelly.