Directions Combine chicken stock, chicken soup, cornstarch, steak seasoning, black pepper, Italian seasoning, and garlic powder together in a slow cooker set. Heat canola oil in a skillet over medium-high heat. Cook and stir broccoli, carrots, and onion in hot oil until onion is translucent, about 5 minutes. Transfer broccoli mixture to slow cooker. Cook on Low for 3 to 4 hours; add Cheddar cheese and stir until melted. Ladle soup into bowls and top each portion with a dollop of sour cream.