Wash and slit green chillies carefully only on one side, remove seeds and keep aside.
Take gram flour in a bowl and add salt to taste, turmeric powder and one teaspoon of red chilli powder.
Add sufficient water to gram flour to form a batter of coating consistency.
Heat one teaspoon of oil in a pan on medium heat, add onion and cook, stirring continuously, till onion turns light golden brown.
Add mushrooms and cook for another two to three minutes, stirring frequently.