Heat the oil in a large pan over medium heat.
Once hot, stir in the cumin seeds and garlic paste. Sauté for approximately 1 minute, stirring continuously until fragrant, taking care not to burn the garlic.
Stir in the finely chopped onion and cook for 4–5 minutes, stirring occasionally, until softened and lightly golden brown.
Mix in the chopped tomatoes and continue cooking for 4–5 minutes, stirring occasionally, until they soften and begin to break down into a thick mixture.
Sprinkle in the spices and salt, stirring thoroughly to coat the onion and tomato mixture. Cook for 3–4 minutes over medium heat, stirring regularly to prevent the spices from sticking or burning.
Pour in the water and stir well to combine everything. Continue cooking for another 3–4 minutes, allowing the masala to thicken and the oil to begin separating from the mixture.
Stir in the prepared apple gourd, ensuring all the pieces are evenly coated in the masala. Cook uncovered for 5–10 minutes over medium heat, stirring occasionally to allow the flavours to develop.
Add the sliced bell pepper and gently mix until evenly distributed throughout the pan and coated in the spiced mixture.
Cover the pan with a lid and reduce the heat to medium-low. Allow everything to cook for 15–20 minutes, stirring occasionally, until the apple gourd is tender and the bell pepper has softened.
Check periodically and add a small splash of water if the mixture becomes too dry or begins sticking to the pan.
Sprinkle the freshly chopped coriander over the cooked vegetables and gently stir to combine. Remove from the heat and serve hot with roti, chapati or rice.