Add coconut oil to a large skillet and preheat on medium high. Add chopped onions and cook for 2 minutes until translucent. Add chicken breast pieces and cook for 3 minutes before stirring in curry powder, salt, pepper and coconut milk. Reduce heat, cover and simmer for 3 minutes. Stir in flour before adding bell peppers and simmer for another 5 minutes, stirring occasionally. Serve chicken curry over rice.