In a large skillet over medium heat, brown the ground beef with the diced onion, bell pepper, and minced garlic. Cook until the beef is no longer pink and the vegetables are soft.
Drain any excess grease, then transfer the mixture to your slow cooker.
Add the sweet potato, Yukon gold potatoes, carrots, celery, fire-roasted tomatoes, tomato paste, beef broth, Italian seasoning, salt, and pepper into the slow cooker. Stir to combine.
Set your slow cooker to low and cook for 8–9 hours or high for 5–6 hours.
An hour before serving, add the green beans and kale to the soup. Stir to incorporate and put the lid back on.
If you’re using frozen green beans, add them 30 minutes before serving instead of an hour.
Taste and adjust the seasoning with additional salt or pepper if needed. Serve warm and enjoy!
