Sift together the flour, milk powder, sugar, yeast, and salt in a large bowl.

Add water and oil to the dry ingredients.

Knead the mixture until a smooth dough forms.

Cover the dough and let it rise in a warm place until doubled in size (approximately 1 hour).

Divide the dough into small balls (about 3 cm in diameter).

Arrange the dough balls in a greased baking pan.

Brush the tops of the buns with egg yolk.

Sprinkle sesame seeds over the egg yolk.

Bake in a preheated oven until golden brown.