Before You Start
Combine all ingredients into the bowl of a stand mixer. With the dough hook in place, mix on low until the dough begins to come together. Increase the speed to mediumlow and continue mixing for 7 minutes. If the dough seems too dry, add 5-10 mL of water. Conversely, if the dough seems too moist and is not pulling away from the sides of the mixing bowl, then add 3-5 g of all-purpose flour.
Remove the dough from the mixing bowl and place inside an oiled or sprayed, rigid container. Cover with plastic wrap or a wet towel and allow the dough to rise until doubled in size.
Remove the dough from the proofing container and place on the counter. Divide the dough into two equal pieces. Shape each piece into a log. Divide each log into 10 pieces. You should now have 20 equal pieces of dough. Roll each piece of dough into a ball, lightly dust each ball with flour, and place on the counter. Cover with plastic wrap or warm wet towels and allow to proof for 15 minutes.
One at a time, roll out 10 (8 cm) flat circles. Reserve the remaining 10 pieces of dough. Place the 10 rolled-out circles onto the perforated oven pan, which has been greased with cooking spray. Cover with a warm towel and allow to proof for 15 minutes. While the dough is proofing, roll out the remaining 10 pieces of dough and place them on the counter. Cover with a warm towel and allow to proof while you steam the first tray. Place the perforated pan on rack position 2. Turn the convection steam oven on by selecting the Steam Mode set to 100°C. Set a timer for 10 minutes. After the timer goes off, remove the pan from the oven, but leave the oven on. Place the pan on a heatproof surface and remove the steam buns. Respray the perforated pan and place the second batch of proofed buns onto the pan. Return the pan to the oven on rack position 2 and set a timer for 8 minutes (the oven is already preheated so we don’t need to steam the buns as long this time). After the timer goes off, remove the pan from the oven and turn the convection steam oven off. Place the pan on a heatproof surface and remove the steam buns. Use them immediately, or save them for later use.