Add the oil to a Dutch oven or large, deep sauté pan and place over MEDIUM heat. Add the curry and cook, stirring, for two minutes, to toast the curry. Allow the curry oil to brown but lower the heat, if needed, so that it doesn't burn. Stir in the onions and red bell pepper, and cook, stirring, for 2 minutes. Add the garlic and cook for 1 more minute. Add chicken, tossing lightly to coat with the curry oil. Season with salt and pepper, to taste. Cook for 7 to 10 minutes, or until chicken is cooked through and juices run clear.
Add the coconut milk, tomatoes, tomato sauce, sugar, and crushed red pepper to the pan, and stir to combine. Add cauliflower. Increase heat to MEDIUM-HIGH and cook until mixture just comes to a boil. Reduce heat to LOW and simmer, uncovered, stirring occasionally, approximately 30 to 40 minutes, or until cauliflower and bell pepper are tender.