In a small bowl, combine the warm water, sugar, and yeast. Let it sit for about 5-10 minutes until it becomes frothy.
In a large mixing bowl, combine the flour and salt. Make a well in the center and pour in the yeast mixture and olive oil.
Mix until a dough forms, then knead the dough on a lightly floured surface for about 5-7 minutes until smooth and elastic.
Place the dough in a lightly oiled bowl, cover with a damp cloth, and let it rise in a warm place for about 1 hour, or until doubled in size.
In a large skillet, cook the ground beef or lamb over medium heat until browned.
Add the chopped onion and garlic, and cook until softened.
Stir in the chopped green bell pepper, tomatoes, parsley, tomato paste, ground cumin, paprika, salt, black pepper, and red pepper flakes (if using). Cook for another 5-7 minutes until the vegetables are tender and the flavors are well combined. Remove from heat and let it cool slightly.
Preheat your oven to 475°F (245°C) and place a pizza stone or baking sheet inside to heat up.
Punch down the risen dough and divide it into 4 equal pieces.
Roll each piece into an oval shape on a lightly floured surface, about 10-12 inches long and 6 inches wide.
Spread a thin layer of the meat filling evenly over each oval, leaving a small border around the edges.
Fold the edges of the dough over the filling, pinching the ends to seal and form a boat shape.
Carefully transfer the assembled pide to the preheated pizza stone or baking sheet.
Brush the edges of the dough with the beaten egg yolk and sprinkle with sesame seeds if desired.
Bake for about 10-12 minutes, or until the crust is golden and crispy.
Enjoy your meal!