Prepare the Dough: In a large bowl, combine flour and salt. Gradually add warm water and olive oil, mixing until a shaggy dough forms. Knead on a lightly floured surface for 5-7 minutes until smooth and elastic. Cover the bowl with a damp cloth and let it rest for at least 30 minutes at room temperature.

Prepare the Filling: While the dough rests, heat 1 tbsp olive oil in a pan over medium heat. Add chopped onion and sauté until softened, about 3-5 minutes. Add the chopped spinach and cook until wilted, squeezing out any excess water. Remove from heat and let it cool slightly.

Combine Filling: In a bowl, combine the cooled spinach and onion mixture with crumbled feta cheese, black pepper, and salt to taste. Mix well.

Roll Out Dough: Divide the rested dough into 4 equal pieces. On a lightly floured surface, take one piece and roll it out into a very thin oval or rectangle, about 10x12 inches (25x30 cm). The thinner the better!

Fill and Fold: Spread about a quarter of the filling evenly over one half of the rolled-out dough, leaving a small border around the edges. Fold the other half of the dough over the filling to create a half-moon or rectangular shape. Press the edges firmly to seal. You can crimp the edges with a fork if desired.

Cook Gözleme: Heat a large non-stick griddle or frying pan over medium-high heat. Place one gözleme on the hot griddle (no oil needed initially, as the dough has oil). Cook for 3-5 minutes per side, or until golden brown spots appear and the dough is cooked through.

Serve: Once cooked, remove from the griddle. Traditionally, gözleme is brushed with a little melted butter or olive oil just after cooking for extra flavor and softness. Cut into halves or wedges and serve hot. Repeat with the remaining dough and filling.