Peel and grate 500 grams of bottle gourd (lauki). Squeeze out the excess water from the grated lauki and keep it aside.
In a mixing bowl, add the grated lauki, 100 grams of gram flour (besan), 1/2 teaspoon of red chili powder, 1/2 teaspoon of garam masala, 1/2 teaspoon of turmeric powder, salt to taste, and chopped coriander leaves. Mix well to form a thick batter.
Heat oil in a deep frying pan. Shape the lauki mixture into small balls (koftas) and deep fry them until golden brown. Remove from oil and place them on a paper towel to absorb excess oil.
In another pan, heat 2 tablespoons of oil. Add 1 teaspoon of cumin seeds and let them crackle. Add 1 finely chopped onion and sauté until golden brown.
Add 1 teaspoon of ginger-garlic paste and cook for a minute. Add 2 finely chopped tomatoes and cook until they turn soft and mushy.
Add 1/2 teaspoon of turmeric powder, 1 teaspoon of coriander powder, 1/2 teaspoon of red chili powder, and salt to taste. Cook the spices for 2-3 minutes.
Add 1 cup of water and bring the gravy to a boil. Lower the heat and let it simmer for 5-6 minutes.
Gently add the fried lauki koftas to the gravy and cook for another 2-3 minutes.
Garnish with chopped coriander leaves and serve hot with roti or rice.