Preheat a large pot over medium heat. Add the olive oil and heat until shimmering. Add the sausage and cook, undisturbed, until golden brown, around 4 minutes. Flip each piece of sausage and brown the other sides, 4 more minutes. Add the onion, red pepper, green pepper and yellow pepper and season with salt. Cook, stirring occasionally, until the onions are translucent and the peppers are slightly tender, around 6 minutes. Add the garlic, Italian seasoning, fennel seeds and cook, stirring, until fragrant, around 1 minute.

Add the Kettle & Fire Chicken Bone Broth and use a wooden spoon to lift any brown bits off the bottom of the pot. Add the crushed tomatoes, potatoes and black pepper and stir to combine. Raise the heat to high, bring the liquid to a boil, cover with a lid, reduce the heat to medium-low and cook until the potatoes are fork-tender, around 15 minutes. Taste the soup for seasoning and adjust with salt and pepper as desired. Add the basil and stir through to combine.

Ladel the soup into individual bowls, finish with a drizzle of olive oil and garnish with fresh basil and chile flakes, if desired. Serve immediately.