Wash the green chillies well with water and cut them into small pieces.
Grind coriander seeds, fennel seeds, cumin seeds, black pepper, dry red chilies, garlic cloves, and ginger pieces coarsely in a mixer jar.
Heat mustard oil in a pan and add mustard seeds, cumin seeds, mangrayla, carom seeds, asafoetida, pickle masala, and the ground spices. Fry for 1-2 minutes on low flame.
Add the cut green chillies to the pan and fry for 2-3 minutes on low flame while stirring occasionally.
Add red chilli powder, Kashmiri red chilli powder, salt, and turmeric powder to the pan and mix well.
Fry for another 2 minutes on low flame while stirring occasionally.
Add water to the pan and cover it. Cook on low flame for 2-3 minutes.
Turn off the gas and add beaten curd to the pan.
Mix well and cook on medium flame until the curd starts boiling.
Lower the flame, cover the pan, and cook for 5-7 minutes or until the chillies are soft and oil separates.
Add mango powder to the pan and mix well. Cook for another minute on low flame.