In a medium saucepan, mix together diced apples, sugar, butter, cornstarch, spices, and water. Cook this for about 7 minutes or until the mixture becomes a sauce and starts to thicken.
To make the apple strudel a bit more decorative, use a knife to cut lines (about 16 or so) into each outer third of the puff pastry, forming strips. Then criss-cross the strips onto the filling.