Add the active dry yeast into the lukewarm water, mix and allow to sit for 10 minutes. You know the yeast is active if it blooms. If you are using instant yeast, skip this step.
1 tbsp active dry yeast or instant yeast, 2 tbsp lukewarm water
In a saucepan, add the tangzhong ingredients and cook, continuing to stir over low heat until a paste forms. Should be thick and you will be able to pick all of it up with a spoon.
2 tbsp flour, 2 tbsp water, 4½ tbsp milk
Add your yeast mixture and tangzhong along with the remaining dough ingredients except for the softened butter in a stand mixer bowl. If you are using instant yeast, add the yeast and water in at this stage as well. Mix on low speed for 5 minutes or until a proper dough forms.
Tangzhong, Yeast mixture, 2⅓ cup AP flour, ¼ cup sugar, 1 tsp salt, ½ cup milk, 1 large egg
Add your softened butter, 1 tbsp at a time and mix on medium speed until the butter is fully incorporated and the dough is very smooth. If your dough is too sticky, add more flour 1 tbsp at a time until manageable.
3 tbsp softened unsalted butter
Allow your dough to proof in a bowl, covered with plastic wrap for 1.5 hours or until doubled in size.