Add the flour and the water to a saucepan. Heat over low-medium heat, constantly whisking, until it reaches a temperature of 150°F (65°C). Note: If you don't have a thermometer, remove from the heat as soon as the flour mixture has thickened.

Transfer to a small bowl and cover with plastic wrap. Let it sit at room temperature for 2 hours or overnight in the refrigerator.

Knead: Add the bread flour, instant yeast, and sugar to the bowl of a stand mixer fitted with the dough hook. Add the prepared Tangzhong, water, oil, and salt.

Knead on medium speed for about 5 minutes or until the dough is smooth. Be aware that the dough will be very soft; this is normal. Do not add more flour.

First rise: Lightly grease a glass bowl with oil. Transfer the dough to the bowl and cover it with plastic wrap or a clean kitchen towel. Let the dough rise in a warm place for about 1 hour or until it has doubled in volume.

Lightly grease a 1 Pound Pullman Loaf Pan with oil (or line it with parchment paper).

Once the dough has risen, punch it down to release the air inside. On a well-floured surface, shape the ball into a log the size of your loaf pan. Transfer the dough to the prepared loaf pan and close with the lid.

Second rise: Let the dough rise a second time for 45-60 minutes in a warm environment (you can place it in the oven with the light on). Do not try to open the lid.

Bake: Near the end of the rising time, preheat the oven to 355°F (180°C). Bake the loaf for 30 minutes. Remove the pan from the oven and let it cool for 15 minutes before opening the lid.

Transfer the sandwich bread to a cooling rack to cool completely. Store the sandwich bread wrapped for up to 5 days at room temperature or 7 days in the refrigerator.