Peel Karele and keep its peel separate. Chop Karele and add namak to both peel and chopped Karele for around 2 hours. Wash them thoroughly under running water. Chop onions and wash them too.
Burn mustard oil. Once it cools off, fry onion.
Once onions are transparent and light brown, take them out in a bowl.
Separate the above mentioned masalas in a bowl.
Add theses masalas to the oil in which you had fried onions. Make sure that oil is not hot (just warm enough) else it will get burnt.
Add rest of the karelas and green chilii. Add salt and mix well. Cover with lid.
After its almost cooked, add the peel of Karela. Since it doesn't require much cooking, we have added it later. Cook for one-two min.
Add onions to the cooked Karela.
Now the Karelas are ready.
Serve it with Paranthas.