Sift together, flour, salt and baking powder. Mix in butter until it looks like bread crumbs. Mix in water slowly to make a stiff paste. Knead lightly. Season beef with salt and pepper. Saute in a pan until well browned. Add onions and potatoes. Saute for 15 minutes. Add enough water to cover the indredients. Roll out dough until it is just smaller than the pot opening. Lay dough on top of stew. Reduce heat to low and simmer for 1 hour. When done cut crust into 4 pieces, arrange in bowl and serve stew over the top.