For the bread dough: Dissolve the yeast in the warm water and let it sit stand for 5 minutes.
In a separate bowl mix the flour, sugar and baking powder. Mix yeast water and dry ingredients with oil in a stand mixer using a dough hook for 10 minutes or until the dough becomes elastic and smooth.
Shape the dough into a ball and put it back in the bowl, cover with plastic wrap, and let it rise for 30-40 minutes until doubled. Deflate the air from the dough and it's ready to use.
For the filling: Chop the vegetables finely, and grate the ginger. Mix well all the ingredients, along with prepared vegetables, for the filling in a bowl.
Cut the prepared dough into 8 equal pieces and shape each into a ball. Roll a ball into a 5" (12.5cm) round, and put 1/8 of the meat mixture in the middle of the dough. Pinch the dough to wrap the filling, and shape into a ball (watch our video to see exactly how). Repeat for the remaining dough and filling to make 8 Nikuman balls.
Place the Nikuman balls on 3" (7.5cm) parchment paper squares. Put them in a hot steamer (place them 2" or 5cm apart), and cook at medium high heat for 10- 12 minutes.