Mix 3 cups of flour, yeast powder, sugar and salt for use;

Second step

Put 2 eggs, 1 yolk, water and butter into the bowl of the kitchen processor, then add the above dry powder and stir with a stirring hook at low speed for 5 minutes (I stirred for about 8 minutes);

Third step

Add the remaining flour appropriately. Add a tablespoon if necessary (if the dough is basically on the mixing hook and the bowl wall is basically smooth, there is no need to add flour)

Fourth step

Take down the dough, put it in the pot, cover it (or seal it with food film), and ferment for 1.5-2 hours;

Step five

When the dough is fermented to twice its size, knead it back to its original size and ferment it to twice its size again (about 1.5 hours).

Step 6

Take out the fermented dough, divide it into 12 embryos, knead it into small bread embryos, put it in a baking pan (two baking pans are needed and oiled), seal it again, and ferment it to twice the size, about 1.5 hours;

Step 7

Brush the egg white on the fermented steamed buns and sprinkle with sesame seeds;

Step 8

Preheat the oven to 375/190 C and bake at the bottom of the oven for 20 minutes until the surface turns golden yellow.