Mix flour, whole wheat flour, and salt in a large mixing bowl, or the bowl of a stand mixer. Create a well in the center and add the olive oil and water. Mix until a dough forms. Knead the dough on a lightly floured surface for about five minutes, or in the stand mixer on low speed for 5 minutes, until smooth and elastic. Cover the bowl containing the dough with a plate or damp kitchen towel and let it rest for thirty minutes.
While the dough rests, prepare the filling. Start by cooking the potatoes in boiling water until tender, then drain and mash them in a large bowl.
Heat the olive oil over medium-high heat in a skillet. Add the leeks and sauté for 4 minutes until soft.
Add the cumin seeds, coriander seeds, black pepper, sumac, Aleppo pepper flakes, and salt. Cook for an additional 2-3 minutes.
Remove from heat and stir in the mashed potatoes, parsley, and cilantro (fresh coriander leaves). Mix until well combined.
Divide the rested dough into eight equal pieces (about 85 g. each) and roll each piece into a ball. On a floured surface, roll out each piece of dough into a thin circle, about 8 inches (20 cm.) in diameter. Place a ¼ cup spoonful of the potato filling on one half of each circle.
Using a pastry brush or wet finger, slightly moisten the perimeter of the dough with a small amount of water. Then, fold the dough over to enclose the filling. Press the edges to seal.
Heat 2 tablespoons of olive oil over medium heat in a large skillet. Pan-fry the filled flatbreads in batches until golden and crisp, about 4-5 minutes on each side. Add more oil in between batches as needed. Transfer the cooked flatbreads to a wire rack to drain excess oil before serving.
Serve the bolani hot, or at room temperature, garnished with chopped parsley and minced green chilies if desired.