Sift flour, sugar, salt, matcha, and baking powder into a large bowl. Make a well in the middle. Fill well with warm low fat milk and yeast. Gently stir the water with a spatula to dissolve the yeast.
Then mix to form a soft dough. With clean hands, knead dough in the bowl for about 5 minutes. Cover bowl with plastic wrap and allow to rest for 10 minutes.
Add vegetable oil and knead to get oil incorporated into dough. Remove from bowl and continue to knead on a flat surface for another 8 to 10 minutes until dough is nice and smooth.
Put dough back into the bowl and cover with plastic wrap. Allow to rise in a warm place for 1 to 1½ hours or until double in size.
Prepare 10 pieces of 2x2 inch wax paper on a large platter.
When dough is ready, remove from bowl. Gently punch down and divide into 10 equal portions. Form into balls and flatten into disks of about 3 inches in diameter. Add a rounded tablespoon of red bean paste in the middle of dough. Gather up the sides to seal.
Place seam side down onto wax paper. Repeat with remaining dough. Cover with plastic wrap and allow prepared buns to rise for another 15 minutes.
Prepare a steamer and allow water to come to a boil. Place buns in steamer, place lid on, and steam for 12 minutes. Remove lid carefully to avoid water from dripping onto buns.
Leftover steamed buns may be kept in the freezer. When required, re-steam frozen buns for 8 to 10 minutes.