01 - In a large bowl, combine the flour and salt. Add the lukewarm water and olive oil, stirring until a rough dough forms. Turn out onto a lightly floured surface and knead for 5 to 7 minutes until smooth and elastic. Cover with a damp cloth and let rest for 20 minutes.
02 - Heat 1 tablespoon olive oil in a skillet over medium heat. Add the onion and sauté until softened, about 2 to 3 minutes. Add the chopped spinach and cook until wilted. Remove from heat and let cool slightly, then stir in the crumbled feta, black pepper, and red pepper flakes. Mix thoroughly.
03 - Divide the rested dough into 4 equal portions. On a floured surface, roll each piece into a thin oval or rectangle approximately 1/8 inch thick.
04 - Place one quarter of the spinach and feta filling on one half of each rolled dough piece, leaving a small border around the edges. Fold the dough over to enclose the filling and press the edges firmly to seal.
05 - Heat a large skillet or griddle over medium heat. Brush each gözleme lightly with olive oil or melted butter. 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.