Heat the oil in a large saucepot or Dutch oven over medium-high heat. Once the oil is shimmering, add the onion, carrot, celery, garlic, and red pepper flakes. Season with salt and pepper and cook until vegetables sweat, 5-7 minutes. Push the vegetables to the side and add in the turkey meat. Crumble and season with the Italian seasoning, salt, and pepper. Cook until browned and no longer pink on the inside, about 7 minutes. Add the crushed tomatoes, and chicken broth. Raise the heat to high and bring to a boil and then reduce the heat to medium and let simmer, about 15 to let the flavors develop.