Mix besan, red lentil flour and plain flour with baking soda, turmeric, red chilli powder, ajwain and salt.
Add the water and oil, and knead into a soft dough. Divide into small balls.
Bring water to a boil in a saucepan and immerse the balls. Cook for 10 minutes.
Remove the dough balls and cool until safe to handle.
Add grated potatoes, dried mint and amchur to the cooked dough. Re-knead until smooth and workable for a fine sev press. Add a little more water or oil only if needed.
Press thin strands through a fine sev-making plate onto perforated parchment or the air-fryer insert. Spread loosely rather than piling them up.
Air fry at 150°C for 6–7 minutes, checking closely near the end as the thin strands can burn. Cool before serving.