Preheat oven to 400 degrees.
Mix together flour and baking powder.
Add in salt, 1/4 cup oil, 1/4 cup water, 1 egg and 1 egg white.
Mix until you have a workable dough. Set aside.
Mix together beef, chopped onions, 1 egg, sweet potato, salt, pepper and gravy.
Roll out your dough until it is thin, about a 1/8 inch.
Cut out as many circles as you can, and add a dollop of filling to each one.
Scrunch up the sides and fold together to make dumplings.
Take 1 egg, and brush on all knishes.
Bake for 15-20 minutes on a cookie sheet lined with foil until the filling is cooked and dough is golden brown.