Add salt to the chopped bottle gourd pieces, cover and keep aside for 15 minutes.
In the mean time, heat 1 tsp oil and sauté coarsely chopped onion and green chilies until translucent. Remove from heat and when cool enough to handle, grind into a smooth paste.
After 15 minutes, rinse the pieces with water, squeeze out the excess water and keep aside.
Heat 1 tbsp oil in a large sauté pan; add the finely chopped onions and sauté till lightly browned around the edges.
Add the bottle gourd pieces; cover and cook on medium low flame until the pieces are ¾ cooked, about 10, 15 minutes.
At this point add all the other ingredients, tamarind and all the powders, salt; mix well; cover and cook until the bottlegourd is completely cooked, another 5-10 minutes. Add water if the gravy seems to be too thick.