Add salt to bitter gourds and rest for 30 mins to 1 hour or until water releases.
Rinse under water thoroughly until the bitterness has gone. Drain and deep fry in oil until color changes and crispy. Strain and keep aside.
Now, in another pot, heat oil. Add onion and cook until translucent. Add chilies and cook for a minute. Add ginger garlic paste and cook for 2-3 minutes.
Now, add tomatoes, add water. Cover with lid and let cook in low flame until tomatoes are soft.
Take the lid off, add salt, chili powder, chili flakes, turmeric powder and cook for 4-5 minutes on medium heat. Add fried bitter gourds and cook for 7-8 minutes.
Add tamarind pulp and garam masala, give it a good mix and cook for 2-3 minute on low heat.
Serve and garnish with coriander.