Cook basmati rice in water until fluffy; spread on a tray to cool.
Heat vegetable oil in a skillet, crackle mustard seeds and curry leaves.
Sauté chopped onion, ginger paste, and green chili until onions turn soft.
Add chopped tomatoes, turmeric powder, and salt; cook until tomatoes turn completely soft and mushy.
Add cooked rice to the pan and gently fold until rice is coated and heated through.