In a medium bowl, combine the crumbled feta, ricotta, Greek yogurt, one egg, black pepper, and a pinch of salt. Mix until creamy and well combined. The mixture should be spoonable, not runny.

On a lightly floured surface, unroll the thawed puff pastry. Cut each sheet into 9 equal squares using a knife or pastry cutter. Keep the pastry cold as you work for easier folding.

Spoon about 1 tablespoon of the cheese mixture into the center of each pastry square. Fold each square diagonally into a triangle. Press edges to seal, then crimp with a fork to lock in the filling.

Arrange bourekas on a parchment-lined baking sheet. Beat the second egg and brush it over each boureka. Sprinkle with sesame seeds.

Bake at 375°F (190°C) for 20–25 minutes, or until puffed and golden brown. Let them cool for 5 minutes before handling.

While the bourekas bake, stir together tahini, lemon juice, minced garlic, and salt in a small bowl. Slowly whisk in the water, one tablespoon at a time, until smooth and pourable.

Using a sharp knife, cut a small slit in the top of each boureka. Gently stuff with chopped egg, pickles, tomato, and olives if using. Don’t overfill—just a spoonful or two does the trick.

Drizzle tahini sauce over the filling. Add a little schug or harissa if desired. Gently close the top or leave slightly open for a layered look. Serve warm or at room temperature.