Heat up a pan and add 5 tbsp vegetable oil. When hot, add cumin seeds if using. When the seeds turn color and give off their smell, add sliced red onion and a pinch of salt. Sauté until golden brown. To save time, cut chicken while onions are cooking.
Add chicken, turmeric, chili powder, garlic and ginger powder, coriander, garam masala and 3/4 tsp salt. Sauté 5 minutes. Cover and cook until chicken is tender. Stir occasionally and add a little water if chicken sticks to bottom of pan.
When chicken is cooked, add tomato sauce and sugar. Stir and cover, cook for 5 minutes until tomato sauce separates from oil and there is no raw taste of tomato. Stir occasionally. Add milk, butter, kasoori methi if using and simmer for 2 minutes. Taste and adjust salt/sugar. Add more milk or a little cream depending on the consistency you like.
*** Dairy Free Option - use chicken curry after tomato sauce is done cooking or add a little coconut milk to make curry creamy and simmer for 2 minutes.