Add the onion to a large pot over medium heat with ONLY ½ cup of the broth and sauté for 5-8 minutes until tender, stirring frequently. Add the garlic and cook another minute. Add the remaining 4 cups broth, rice, tomato sauce, Italian seasoning, salt, pepper and chili powder or chili flakes. Stir well and bring to a high boil. Once boiling, turn down to medium-low and cover and cook for 10 minutes until the rice is tender.
Once the rice is tender, add the drained beans and cook another 5 minutes. Taste and add any additional salt/pepper if needed. Add the fresh basil and let the soup sit for 5-10 minutes before serving. It will thicken up a lot as it sits because of the rice.
