In a bowl, mix flour, salt, and yeast (if using). Add warm water and knead to form a smooth and elastic dough. If it is too dry, add a little more water; if too sticky, add flour.
Cover the dough and let it rest for 30 minutes.
Bolani consists of a simple bread dough filled with a spicy mixture. It is crucial that the dough sheet is thin and the filling is evenly spread. If you choose to bake instead of fry, brush them with oil and bake at 185 °C (365 °F) for about 20 minutes until golden and crispy.
In a bowl, mix flour, salt, and yeast (if using). Add warm water and knead to form a smooth and elastic dough. If it is too dry, add a little more water; if too sticky, add flour.
Cover the dough and let it rest for 30 minutes.
Boil the potatoes in their skins, peel, and mash them. Let them cool.
In a frying pan with a little oil, sauté the chopped leek until soft (about 5 minutes).
In a bowl, mix the mashed potatoes, sautéed leek, chopped chillies (if using), fresh and ground coriander, salt, and pepper. Mix well.
Divide the dough into 8–10 equal balls. Roll each ball into a very thin round or oval sheet (about 20-25 cm in diameter).
Spread a thin layer of potato filling over half of the sheet (on one side only), leaving the edges clear.
Fold the empty half over the filling and firmly pinch the edges shut (you can use a fork to seal), creating a half-moon shape.
Heat 1-2 cm of oil in a large frying pan (or use only a small amount of oil for shallow frying).
Fry the Bolani flatbreads over medium heat until they are golden-brown and crispy on both sides (about 3-5 minutes per side).
Drain the finished flatbreads on paper towels.
Prepare the Chatni: mix yogurt, garlic, salt, and mint.
Cut the Bolani into smaller pieces and serve warm with the cold garlic-yogurt sauce Chatni.