Heat oil and add cumin seeds, sauté until fragrant, stir in onions, ginger and chilies, cook until soft.
Add soaked chana dal, turmeric, chilli powder, garam masala, amchur and salt, mix well.
Add water, cover and cook until dal softens but doesn’t turn mushy. Cool completely.
Prepare patti strips, brush edges with water, add filling and fold into triangles or squares.
Preheat air fryer to 185°C/365°F for 5 minutes.
Brush samosas with oil and arrange in a single layer.
Air fry 14–15 minutes, flipping once and brushing oil for even browning.
Serve hot with coriander-mint chutney or tamarind chutney.