Prepare Daal: In a pot, add cooking oil and onion, fry until light golden.
Add spices: Add cumin seeds, tomato, garlic, green chilli, ginger, mix well and cook on medium flame for 2-3 minutes.
Add powders: Add red chilli powder, turmeric powder, kashmiri red chilli powder, mix well and cook for 1-2 minutes.
Add lentils: Add split Bengal gram and split pigeon pea, mix well.
Cook lentils: Add water, mix well and bring to boil, cover and cook on low flame until lentils are tender (about 1 hour).
Mash Daal: Turn off the flame and mash well with the help of a masher.
Add hot water: Turn on the flame, add hot water and mix well.
Season Daal: Add pink salt, coriander seeds, crushed pickle, mix well and set aside.
Prepare Achari Mirch Tadka: In a small bowl, add crushed pickle, coriander seeds, cumin seeds and mix well.
Stuff chillies: Stuff green chillies with prepared achari masala.
Fry Tadka: In a frying pan, add cooking oil, garlic and mix well. Add cumin seeds, button red chillies, achar stuffed chillies and fry until golden.
Finish Tadka: Add kashmiri red chilli powder and stir well.
Serve: Add prepared tadka on daal, garnish with fresh coriander and serve with boiled rice and salad!