Add 1tsp salt to the chopped bitter gourd pieces, mix well and refrigerate overnight.
In the morning, rinse the pieces under water, then drain and squeeze the extra water from the bitter gourd and set aside.
In a pressure cooker, heat 2tbsp oil; add fenugreek seeds and cumin seeds. Once the seeds start to splutter, add the onions and green chilies. Cook till the onions are translucent and turning lightly brown around the edges.
Add the ginger-garlic paste and cook for 1 minute.
Add the bittergourd pieces and saute for 8~10 minutes or until the pieces are almost cooked through, but not completely tender.
Add salt, red chili powder, ground coriander and the chopped tomatoes. Mix well and cook for about 2~3 minutes.
Close the lid and cook for 1~2 whistles. Let the pressure subside, open the lid and add the jaggery (if using) and mix well. If the gravy is looks too thin, then cook till you get the desired consistency.
Garnish with chopped cilantro and serve with steamed rice.