A Tangzhong starter / Water roux starter is a mixture of flour and water. That is to combine together one portion of bread flour and five portions of water by weight in a pot. Heat up the mixture to bring out the gelatinization of starch in flour. What makes the bread baked with this kind of starter difference is Starch Gelatinization, which helps to engage more water, namely more water will be absorbed, to provide a characteristic softer, more elastic-textured bread. Moreover, the bread will have long-lasting freshness.
In a bowl, whisk together the water and the flour until the mixture is well blended and lump free. Stir the mixture while it cooks over the medium heat to reach 65C/150F. It takes about 2-3 minutes.
Remove from heat and cover loosely with plastic wrap to prevent from drying. Store the starter in the refrigerator after completely cooling down. To use the starter, measure out the amount called for in a recipe and let it warm to room temperature. Unlike sourdough starter, this special Tangzhong starter doesn't improve its flavour with age. So it's preferably to use up in 3 days.