In a bowl, mix flour and salt. Gradually add warm water and olive oil, mixing until a dough forms.
Knead the dough on a floured surface for about 5 minutes until smooth. Cover with a damp cloth and let it rest for 30 minutes.
For the filling, heat a pan over medium heat and cook the ground beef and onion until the meat is browned. Add spinach, cumin, and black pepper, and cook until the spinach is wilted.
Divide the dough into 4 equal pieces. Roll each piece into a thin circle on a floured surface.
Place a portion of the filling on half of each dough circle, then fold over to enclose the filling. Press the edges to seal.
Heat a large skillet over medium heat and cook each gozleme for about 3-4 minutes on each side until golden brown and crispy.