Season the chicken with salt and pepper.
Heat the oil in a saute pan over medium-high heat. Add the curry powder and cook for 2 minutes. Stir in the onions and cook until they start to soften, 2-3 minutes. Add in the garlic and cook for 1 minute. add the chicken and stir to coat with the curry oil. Reduce the heat to medium and cook until the chicken is cooked through, 7-10 minutes.
Pour in the coconut milk, tomatoes, tomato sauce and sugar. Simmer, stirring occasionally, for 30-45 minutes.
