Measure the ingredients.

Except for the ice water and butter, place the other ingredients in a mixing bowl. Mix while gradually adding ice water until the dough is smooth and elastic. Add the unsalted butter at low speed and continue mixing until the butter is incorporated into the dough.

Increase to high speed and mix until the dough forms a jagged edge when stretched. Remove the dough, shape it into a ball, and place it in a bowl.

Cover with a damp cloth and let it rise in a warm place for 30 minutes.

Divide the dough into 3 equal parts, each weighing about 240 grams. Shape into balls and let rest for 10 minutes.

Take one piece of dough, roll it out, and fold it into thirds.

Let it relax for another 10 minutes. Take one piece of dough, press out the air, and turn it over.

Roll it once, then flip the dough so the unrolled side is up, and roll it down again.

Repeat this action 3 times. Finally, pinch the seam tightly. The shaped bread should be about 11-12 inches long. Spray the smooth side with water, coat with oats, and place the bread neatly on a baking sheet.

After a final rise of 20 minutes, spray more water on the dough surface. Bake in the oven at 356°F (180°C) for 20 minutes (bake for 13 minutes, then rotate and bake for another 7 minutes).

Remove from the oven and let cool.

Cut the bread into 2 pieces, slice open the middle, and fill with your favorite ingredients to make a delicious submarine sandwich.

If you can't finish the bread, freeze it for storage.

Thaw and eat, or toast in a small oven for 3 minutes for a soft and tasty treat.