In a mixing bowl, combine flour and salt. Gradually add warm water and olive oil, kneading until smooth dough forms. Cover and rest 30 minutes.

Heat olive oil in a pan over medium heat. Sauté onion until translucent. Add spinach and cook 2–3 minutes. Remove from heat and mix in feta, salt, pepper, and red pepper flakes.

Divide dough into 4 portions. Roll each into an 8–10 inch circle on a floured surface.

Place filling on half of each circle. Fold dough over to cover filling and press edges to seal.

Heat a non-stick skillet over medium heat. Cook Gozleme 2–3 minutes per side until golden and crisp. Brush with olive oil if desired.

Slice and serve warm with yogurt, lemon, or fresh herbs.