In a soup pot, warm the oil over medium heat. Add the onions and cook for 10 minutes, stirring occasionally, until the onions are soft, tender and slightly browned. Add the garlic and cook for about a minute. Add the bell peppers and the dried spices. Cook the the peppers for a minute or two, and then add the tomatoes. Crush the tomatoes quickly; squeezing them with your hands while they are still cool or using the back of a spoon or with a few pulses of an immersion blender. Add the chicken and bring to a boil and then reduce heat to a simmer for 20 minutes.
After simmering, add the basil (if using fresh basil) and simmer for an additional 5 minutes. Serve with the toppings of your choice if desired. Enjoy!