Beat the egg and water in a small bowl to make the egg wash. Keep this aside for now.
Unroll your pastry sheets and cut them into small rectangle strips. Mine were about 2-3 inches wide and 5-6 inches long. These are approximate since I didn't use a ruler to measure them.
Place 1 tablespoon of thick strawberry preserve in the center of the pastry strip.
Fold one side of the strip on top of the filling and then fold the other side of the strip. Press gently so that both ends stick together. Then, flip this strudel onto a cookie tray, lined with parchment paper.
Gently, use a sharp knife to make 3-4 cuts on top of each strudel so that steam can easily escape while baking.
In a small bowl, beat the egg and water to make the egg wash.
Brush the top of each strudel with egg wash and sprinkle some sanding sugar.
Bake at 400 degrees for about 20 minutes or until the strudels are puffy and golden brown. Enjoy!
Notes
Instead of mini strudels, you can also make one big strawberry strudel. Just follow the same steps but don't cut the puff pastry into smaller strips.
You can fill these strudels with any flavor of preserves you like as well as chocolate chips, peanut butter and even Nutella.