First knead the dough. Mix the flour, salt, yeast and sugar in a mixing bowl and add the water. Knead for 7 minutes on speed 1 of the Junbak Chef machine. After kneading, the dough looks like this. Please adjust the amount of water according to the actual situation. The dough for the rolls should not be too soft. If you are kneading by hand, keep kneading the dough for more than 10 minutes until it becomes smooth and elastic. Knead the dough, put it into a bowl, cover with plastic wrap and let it rise at room temperature until 2.5 times its size. Punch down the dough, roll out the air, cover with plastic wrap and relax for 15 minutes, then roll out the dough into a large rectangular shape (sprinkle with a little dry flour to prevent sticking). Spread a layer of vegetable oil on the surface of the sheet. Then sprinkle some chopped green onion (you can leave the green onion out, it will make white rolls). Fold it from one side to the other. After folding, you get a long strip of dough like this. Cut the dough into 12 pieces. Take two small pieces of dough and stack them on top of each other like in the picture. Take a chopstick and press it down from the position in the picture above. Press all the way down to the bottom and then lift the chopstick. The dough you get at this point can be directly fermented and steamed out, a common shape for rolls. If you want to further shape the rolls, you can follow the steps below. Lift up the dough after pressing it with the chopsticks by pinching the ends and stretching it slightly in your hands. Then twist 1 turn like a towel. Finally, fold the ends over to the bottom, gather them at the bottom and pinch them tightly, and the rolls are done. Once the rolls are all done, place them on a greased steamer drawer (leaving enough distance between the rolls). Cover with a damp cloth and let rise in a warm place for 30 minutes. When the rolls have doubled in size, they are ready to be steamed. Place a steamer over cold water, bring the water to a boil, and steam over high heat for 18 minutes. Turn off the heat after steaming, and wait 2 minutes before removing the lid to prevent the rolls from collapsing.