Heat the vegetable oil in a large pot or deep skillet over medium heat.
Add the chopped onion and sauté for 5 minutes until softened and translucent.
Stir in the minced garlic and grated ginger and cook for 1 minute until fragrant.
Add the curry powder, ground turmeric, ground cumin, and chili powder. Stir continuously for 1 minute to toast the spices.
Add the chicken pieces to the pot and cook for 5 minutes, stirring occasionally, until the chicken is lightly browned on all sides.
Add the diced tomato and cook for 2 minutes until it starts to soften.
Pour in the rinsed basmati rice, chicken broth, and coconut milk. Stir to combine all ingredients.
Season with salt and black pepper.
Bring the mixture to a boil, then reduce the heat to low, cover the pot with a tight-fitting lid, and simmer for 20 minutes until the rice is cooked and the chicken is tender.
Remove the pot from heat and let it sit, covered, for 5 minutes to allow the flavors to meld and the rice to finish steaming.
Fluff the rice and curry mixture gently with a fork.
Garnish with chopped fresh cilantro leaves before serving.