Heat oil in a skillet over medium heat. Add the cumin seeds and let them sizzle for a few seconds. Add the chopped onions and sauté until they turn light golden brown.

Stir in the ginger-garlic paste and cook for one minute until the raw aroma disappears. Add the chopped tomatoes and cook until softened and mashed down.

Stir in the Kashmiri red chili powder, turmeric powder, coriander powder, and salt. Cook the mixture until the oil begins to separate at the edges of the pan.

Add the prawns and water to the pan, tossing to coat them in the masala. Simmer over medium-low heat for 4 to 5 minutes until the prawns turn opaque, curl into a C-shape, and are fully cooked.

Sprinkle the garam masala and chopped coriander leaves over the curry. Give it a final stir and remove from heat.