01 - In a large mixing bowl, combine the all-purpose flour and salt. Gradually add the lukewarm water and olive oil, stirring until a rough dough forms. Transfer to a lightly floured surface and knead for 5 to 7 minutes until the dough is smooth and elastic. Cover with a damp cloth and let rest for 20 minutes.
02 - While the dough rests, heat 1 tablespoon of olive oil in a skillet over medium heat. Add the finely chopped onion and sauté for 2 to 3 minutes until softened. Add the chopped spinach and cook until wilted. Remove from heat and let cool slightly, then stir in the crumbled feta cheese, black pepper, and red pepper flakes. Mix until evenly combined.
03 - Divide the rested dough into 4 equal portions. On a floured surface, roll each portion into a thin oval or rectangle approximately 1/8 inch thick.
04 - Place one quarter of the spinach and feta filling onto one half of each rolled dough piece, leaving a small border around the edges. Fold the dough over the filling to enclose it completely and press the edges firmly to seal.
05 - Heat a large skillet or griddle over medium heat. Lightly brush each gözleme with olive oil or melted butter on both sides. Cook for 2 to 3 minutes per side until golden brown and crisp.
06 - Remove from the pan, slice into portions, and serve immediately while hot.