Combine flour, water and salt in a large bowl and mix them well. After you make the dough; close the bowl top with a moisturized piece of cloth or towel and let dough rest about 20 minutes.
While the dough is resting, combine the ground beef, grated onion, salt, ground black pepper, parsley leaves, vinegar and water.
After the dough rest, put some flour to the counter surface and divide the dough to 16 equal pieces. Take the first piece of the dough you divide and roll it until it has 4-5 mm thickness (make thin) and 18-20 cm radius with rolling pin.
Take 1 spoon of filling mix and spread it on to the half side (10 cm) of 20 cm radius dough. Close the empty side of the dough on to the filling spread-ed half and seal it by pressing with your thumb or fork front. Apply the method to the remaining dough pieces.
Heat vegetable oil in a large skillet over medium-high heat. And then put the half-moon shaped dough to the skillet (two by two OR three by three according to the size of your skillet) and cook them until the both sides have golden color.
Put a paper towel onto a serving plate and line up the cooked Çiböreks onto the paper towel to get the excess vegetable oil on them.
Tip: Make sure the vegetable oil has medium-high heat to fry the dough as fast as you can. If the vegetable oil is not heated enough, the dough absorbs the vegetable oil and it is not that we want.