In a bowl, combine the flour and salt. Create a well in the center of the flour, pour in the sunflower oil, and mix by rubbing between your palms until coarse crumbs form. Gradually add the water and knead until a soft dough forms. For convenience, knead in the mixer for 5 minutes. Cover the bowl with plastic wrap and set the dough aside for 30 minutes.
For the filling: Heat the olive oil in a pan and sauté the onion until well browned, about 7-8 minutes. Allow it to cool slightly. In a separate bowl, combine the halloumi, fresh mint, black pepper, caramelized onion, and eggs. Mix well.
Divide the dough into 4-5 pieces and form them into balls. Flour the surface where you will be rolling out the dough and place the balls on it. Roll out one ball at a time with a rolling pin into a large rectangular thin sheet. Place 1 teaspoon of the halloumi mixture on the edge of the sheet and repeat along the entire length of the sheet, leaving a distance of 7-8 cm between each. Fold the dough over the filling and press slightly around the halloumi to seal the edges of the dough. Cut into square pieces, 6-7 cm each, using a knife or a special cutter. If desired, press the edges with a fork.
Heat a saj (or non-stick pan) on the stove and place the pies on top. Cook for 2-3 minutes, turning them to brown evenly on both sides. If you prefer the pies to be soft, place them in a bowl and cover it with its lid.