First, make the syrup. Put the sugar in a suitable pot. Pour the water and lemon juice over it. Once it comes to a boil, leave it for about 15 min. on low heat. Leave it to cool.
Sift the flour with the baking powder in a bowl. Beat the eggs in another bowl. Add the milk, then the oil, vinegar and salt. Begin adding the flour, while stirring with a whisk. Once a ball begins to form, move it over to the counter and finish kneading by hand.
Divide the dough into 3 equal parts. From each of these, make 10 balls. Wrap them with foil, to prevent a crust from forming.
Sprinkle the counter generously with starch. Take 1 ball and roll it out to a circle about 6″ (15 cm) in diameter, while also sprinkling it with starch. Set it aside.
Do this for the rest of the balls of dough - you need to have 3 piles of 10 sheets each, one on top of the other. Sprinkle one of the piles with starch and roll it out to a sheet about 14 1/4″ (36 cm) in diameter. Compare it to the size of the oven dish and cut off any excess.
Move the sheet to the prepared oven dish. Sprinkle it generously with part of the ground nuts. Do this for the other 10 sheets as well. Transfer them onto the filling and sprinkle with the remaining nuts.
Roll out the last 10 sheets and cover the filling. Cut the baklava with a sharp knife as desired. Knead the excess dough again and cut out a decoration from it. Place a flower-shaped piece onto each separate slice and a hazelnut in the middle of each flower.
Melt the butter and pour it over the baklava, making sure it seeps into the cracks. Bake it at 356°F (180 °C) about 1 hour. Take it out of the oven and while still warm, pour the cold syrup over it.
Let the baklava sit overnight.
The number of slices depends on how you cut it and how large each slice is.
The recipe is from my friend Nebibe-Nelly.