How to make
Sift the flour, make a well. Beat the eggs lightly with a fork and pour them into the flour. Add the salt and vinegar and knead a soft dough. It's going to be sticky. Divide it into 7 equal parts, form them into balls. Be sure to flour your hands and dough constantly. Leave the balls to sit for 30 min.
Roll out the balls to thin sheets 1/8 thick. Roll out the sheets one after the other. Smear a 11 3/4″ (30 cm) diameter oven dish well with 3-4 tbsp melted butter. Roll out the 1st sheet, a little wider than the oven dish bottom. Place it in the oven dish, while stretching out its edges to touch the edges of the oven dish to form a kind of border. Sprinkle with melted butter and crumbled feta cheese (try to distribute these out so there's enough for every sheet).
Next comes the bathing part. Prepare 2 other oven dishes. Put 1 of them on the stove to boil with 4 1/5 cups (1 L) water with a pinch of salt. Put the other one nearby, filled with 4 1/5 cups (1 L) cold water.
Start rolling out the sheets 1 by 1, trying to make them a little larger than the oven dish you'll be baking in, since they'll shrink a bit. Be sure you're constantly adding flour or they might stick to the rolling pin and tear.
Carefully transfer the rolled out sheet with the rolling pin to the oven dish with the boiling water to bathe. Leave it to boil 10-15 seconds and then carefully transfer it to the oven dish with cold water using a slotted spoon, to cool. With both hands, carefully lift the sheet from the bottom and place it atop the 1st dry sheet in the main baking dish.
Pour out the cold water and pour in new cold water. Do the same with the hot water every 2 sheets because some of the flour from the sheets will fall into the water, making it sticky. The phyllo has to be well bathed after all, right?
Repeat this process with the next sheet, rolling it out, bathing it in hot water, then in cool water and placing it atop the others, while also sprinkling with butter and crumbled feta cheese.
Place the final sheet at the very top without dipping it in water. Roll it out a bit wider than the others and fold its edges inwards a bit. Sprinkle with the final 2 tbsp melted butter on top.
Bake the phyllo pastry in a preheated 320°F (160 °C) oven for 10 min. Then turn the heat up to 390°F (200 °C) and bake another 15-20 min. Don't sprinkle it with water at the end. Cover with a sheet of paper and a towel. It's going to end up soft, tender, with an appetizing fragrance.
