Take besan, buttermilk, turmeric powder and salt in a large bowl. Mix properly and make smooth batter using a hand blender. Grease a large plate or back side of a thali or an aluminum foil with cooking oil and keep aside.

Pour batter into a heavy bottomed pan or a kadai and cook on low flame. Keep stirring constantly to avoid lump formation.

Cook until mixture becomes thick and does not taste raw.

Transfer a large spoonful of batter over previously greased plate or thali. Spread batter in a thin layer with the backside of a flat spoon or a spatula. Depending on the quantity of the batter and size of a plate, you may need 2-3 plates to spread the whole batter.

Carefully roll each strip into a roll (like a swiss roll) and transfer them to a serving dish.

Heat 2 tablespoons cooking oil in a small tempering pan. Add mustard seeds; when they begin to crackle, add cumin seeds, curry leaves and green chillies and let them cook for around 30-40 seconds. Add sesame seeds only in the end when the sauté is ready.