In a medium saucepan heat oil and curry powder, mix together to make a curry paste. After a few minutes of heating add garlic and onions and saute. The onion should be clear after about 5-8 minutes- that's when you know it's ready.
Add the chicken to the pan and stir well to coat with curry oil. Cook until no longer pink, about 6-8 minutes.
Pour in the can of coconut milk, tomatoes, and tomato sauce. Add the sugar and stir together.
Simmer on your stove on low for about 30-45 minutes, stir about every 5-10 minutes.
Serve over rice.