Remove the black part of the Indian round gourd and make slits in a plus sign.
Mix together coriander powder, cumin powder, dried mango powder, black salt, red chilli powder, ½ tsp garam masala powder, turmeric powder and salt in a bowl.
Heat oil in a non-stick pan.
Stuff gourds with the spice mixture.
Add cumin seeds and green chillies to the pan and sauté.
Add ginger-garlic paste, cover and cook for 2-3 minutes.
Add green chilli paste, mix well. Add stuffed gourds, cover and cook for 6-8 minutes, tossing once a while.
Add button onions. Roughly chop tomatoes and add. Toss to mix. Add left over spice mixture, lemon juice, remaining garam masala powder and 1 tablespoon chopped coriander. Cover and cook for 6-8 minutes.
Remove cover, mix well and serve hot garnished with remaining chopped coriander.