Combine yeast, sugar and warm water in the mixing bowl of a stand mixer. Let stand for 10 minutes. Stir in AP flour, whole wheat flour, matcha powder and salt. Knead until the dough is soft and elastic. Cover with a plastic wrap and proof at room temperature for about 2 hours.
- Place the dough on a floured board and knead it into a loaf. Divide the loaf into 6-8 pieces and let rest for 5 minutes. Sprinkle each small dough with some flour and lightly press them flat. Fold the side of the dough up with your left hand, meanwhile press the upper edge down with your right hand. Repeat this step until you get the shorter edge and slightly round bottom. Pinch them together between the thumb and the index finger of your right hand. Place them on the board and let rise covered until doubled. Repeat the step of folding and pressing.
Place the dough balls in a steamer and process the final proof for about 25 minutes. Use the flour during the whole shaping process. Each small dough needs about 15 extra grams of flour to finish the kneading. So that the texture of the steamed buns would appear thick and with clear layers. To achieve a chewy bun, long proofing time at the final stage should always be avoided. Take away the plastic wrap and steam for 20 minutes over medium heat with a lid covered.