Place the flour in a large bowl. Make a well in the center and add the vinegar, salt, and olive oil.

Gradually add the water and knead until you have a soft dough that doesn't stick to your hands. Cover the dough and let it rest for 30 minutes.

Meanwhile, prepare the filling. In a bowl, crumble the feta and ricotta with your hands. Add the milk and lightly beaten eggs, then mix well.

On a clean surface, sprinkle some cornstarch. Take a piece of dough about the size of a small tangerine. Place it on the floured surface, sprinkle with more cornstarch, and gently flatten it with your hand.

Using a rolling pin, roll out the dough, turning it as you go to keep it as round as possible.

Start wrapping the dough around the rolling pin and gently roll from the center outwards to stretch the dough. Repeat this two or three times, then unroll and roll from the other side. Make sure the surface stays well-floured so the dough doesn't stick.

Once the dough reaches the desired size, wrap it around the rolling pin and lay it out in a greased 10-inch (26 cm) baking pan. Brush with a little olive oil, making sure to get the sides as well.

Let the phyllo sheets hang over the edge of the pan so you can fold them over at the end. Roll out two more sheets the same way, layering them in the pan and brushing each with olive oil.

Add the filling and spread it evenly. Roll out two more sheets to cover the pie, again brushing each with olive oil.

Fold the overhanging bottom sheets over the top, twisting them slightly to form a decorative edge. Brush with a little olive oil.

Sprinkle with a little water and bake in a preheated oven at 350°F (180°C) for about 90 minutes, until golden brown.

Let cool slightly, then cut into pieces.