Finely chop the onion, tomato, garlic, and ginger.
Heat cooking oil in a pan and sauté the onions until they turn brown.
Add garlic and ginger, and sauté for 1 minute.
Add tomatoes and all spices (cumin, coriander, turmeric, chili powder, garam masala, and salt) and cook for 5 minutes.
Add the chicken and stir-fry until the outside is cooked.
Pour in coconut milk and water, cover with a lid, and simmer on medium heat for 15 minutes.
Garnish with chopped cilantro as desired to finish.