Season the chicken chunks with salt and pepper.
Mix curry powder and oil. Heat a large skillet over medium-high heat and add the curry oil mixture. Heat curry oil for 1 minute.
Add garlic and onions and cook for 1 minute.
Add chicken chunks and toss lightly to coat with the curry oil mixture.
Reduce heat to medium, and cook for 7 to 10 minutes, or until chicken is no longer pink in center and juices run clear.
Pour coconut milk, diced tomatoes, tomato sauce, and sugar into the pan, and stir to combine. Cover and simmer, stirring occasionally, approximately 30 to 40 minutes.
Serve immediately, over rice. Enjoy!