Dissolve the yeast in warm water with sugar. Add the flour and salt. Mix well. Knead the dough until it is cool and will not stick to hands. Grease the bowl with vegetable oil and knead the dough further. The oil should soak into the dough. Give the dough 2-3 times. While the dough rises prepare the filling. Boil potatoes in their skins, cool, peel and cut into slices. Fish fillet roll in flour and fry until ready. Onions cut into rings. The finished dough divide into two balls and roll out. The first layer should be about 1 cm tall. Form for baking grease with vegetable oil and put in it the dough, grease with vegetable oil. On the dough put the number of potatoes...

then fried fish fillet...

and on top of onion rings. Cover the pie with a second layer of dough. To seal the edges. Let stand for 5 minutes, then pierce the cake with a fork and bake at 180*C for about 30-40 minutes.

So cake looks in the cut. I only the top layer of thinly unrolled, and you need 0.5-0.7 mm.