To begin, wash the karelas well and slice them thinly. Place them in a large bowl. Add two teaspoons of salt. Mix well and leave aside for at least 30 minutes. This helps reduce the bitterness.
After 30 minutes, wash the karela slices and drain them well.
Heat a cup of mustard oil for deep frying until the smoking point and let it cool a bit.
Deep fry the karelas in batches until they are semi-cooked. Remove and keep aside.
To prepare the masala, heat 2 tbsp of the same oil for added flavor.
Add in the mustard seeds and let them crackle.
Add in the sliced onions, curry leaves, and green chillies. Saute for a few minutes.
Add ginger garlic paste and saute until the onions are translucent.
Next, add in the dry masalas - salt, Kashmiri red chilli powder, cumin powder (jeera), coriander powder (dhania), and amchoor (dry mango) powder. Mix well. Add a bit of water so that the masalas do not burn.
Now add in the fried karela slices. Mix.
Finally, add in tamarind pulp and a bit more water. Mix until the karela slices are well coated.
Cover with a lid and cook for a minute or two. Check the salt and add more if required.
The Chatpate Karele are ready to serve. Garnish with fried curry leaves. Enjoy them with chapattis.