SLICE the bread lengthwise and remove some of the center to make room for the filling.
MAKE a quick version of Russian dressing by mixing the mayonnaise, ketchup, pickle relish and horseradish. Spread mixture generously on the cut sides of the loaf.
On the bottom half, place the corned beef; cover with a layer of cheese slices; spread sauerkraut over the cheese. Cover with the top half of the loaf and press together gently. cut and serve.