4. Step
Add onion and garlic to the pan and reduce the heat to medium. Cook, stirring frequently, until the onion begins to soften, about 2 minutes. Add tomatoes, broth and any spice mixture remaining in the bowl; bring to a boil, scraping up any browned bits. Add the mixture to the slow cooker, along with the pepper strips. Cover and cook on High for 4 hours or Low for 8 hours.