Wash and soak the basmati rice in water for 20-30 minutes. Drain it just before using to ensure the grains remain separate.

In a large pot, heat mustard oil over medium-high heat. Add the whole spices and fry them for 5-10 seconds until fragrant.

Add the sliced onions to the pot and cook until they are golden brown, about 7-10 minutes. Stir occasionally to avoid burning.

Add chicken pieces, garlic paste, ginger, coriander powder, green chilies, sliced tomato, and salt. Cook until the chicken is no longer pink and the tomatoes have softened.

Stir in the drained rice, warm water, and remaining salt. Mix gently to combine all ingredients.

Bring the mixture to a boil, then cover the pot. Lower the heat and let it cook for 10-15 minutes until the water is absorbed.

Let the pilaf rest for 15-20 minutes before serving. Fluff it gently with a spatula and garnish with chopped coriander leaves.