1. Heat the olive oil in a large pot or Dutch oven over medium heat. Add the chopped onion and bell peppers and cook, stirring occasionally, until softened, about 5-7 minutes.

2. Stir in the minced garlic, chili powder, cumin, smoked paprika, and cayenne pepper (if using). Cook for another minute, stirring constantly, until the spices are fragrant.

3. Pour in the crushed tomatoes, diced tomatoes (with their liquid), kidney beans, black beans, and vegetable broth. Stir everything together until well combined. Bring the mixture to a gentle simmer.

4. Reduce the heat to low, cover the pot, and let the chili simmer for at least 15-20 minutes. Stir occasionally to prevent sticking.

5. While the chili simmers, spread the cubed sourdough bread on a baking sheet. You can lightly toast them in a dry pan or oven for a few minutes if you prefer a slightly crispier texture, but it’s not strictly necessary.

6. Once the chili has simmered, remove the lid. Stir in the sourdough bread cubes. Cook for another 5 minutes, or until the sourdough pieces have softened and absorbed some of the chili liquid.

7. Taste the chili and season with salt and black pepper as needed. Ladle the hot chili into bowls, garnish with fresh cilantro, and add any desired toppings.