PIROSHKI - Pontian Greek Vegan recipe

My mother's ancestors are Pontian Greeks, and they passed this recipe from generation to generation.
Here are some informations about the Pontians:
https://en.wikipedia.org/wiki/Pontic_Greeks

INGREDIENTS - PREPARATION

For the dough, start by preparing the yeast with
- 1 1/2 cups of warm water
- 1 tsp sugar
- 1 tbsp flour
Stir and cover with a plastic membrane until it activates
Meanwhile, wash and peel
- 2 lbs (800 gr) potatoes
and boil them till soft
Back to our dough. In a large bowl. mix the activated yeast with
- 1/3 cup olive oil
- 1 tbsp lemon juice
- 1/2 tsp sugar
- 1 tsp salt
Then gradually add
- 3-4 cups of flour
until you get a soft, non sticky dough. Cover the bowl and put it in a warm place for 1-1 1/2 hour, until it doubles its volume.
While waiting, prepare the filling.
To your boiled potatoes, add:
- 1 tsp salt
- 1 tsp oregano
- 1/2 tsp pepper
- 3 tbsp parsley
Mash them up and add
- 2 onions chopped and fried till translucent.
Stir all the ingredients of the filling.
When the dough is ready, separate to 20 pieces. Make a round shape of each piece of dough, fill it with a little bit of the potato filling, close the ends and deep fry it until golden brown on both sides.