Brown the Beef & Aromatics: Heat olive oil in a large skillet over medium-high heat. Add the ground beef and diced onion. Cook for 6 to 8 minutes, breaking up the meat with a wooden spoon, until browned and cooked through. Add minced garlic and cook for 1 minute until fragrant. Drain off any excess grease and transfer meat mixture to a 6-quart slow cooker.

Load the Slow Cooker: Add chopped bell peppers, crushed fire-roasted tomatoes, tomato sauce, beef broth, tomato paste, Worcestershire sauce, Italian seasoning, smoked paprika, garlic powder, onion powder, salt, and black pepper. Stir well until the tomato paste dissolves into the broth.

Slow Simmer: Cover with the lid and cook on LOW for 6 to 7 hours, or on HIGH for 3 to 4 hours, until the bell peppers are tender and the rich tomato-beef broth has deeply developed its comforting flavor.

Incorporate the Rice: Stir the cooked white rice into the slow cooker during the last 20 to 30 minutes of cooking on LOW so the rice absorbs the savory broth without getting mushy. (Pro-tip: If you plan to freeze or store leftovers, spoon cooked rice directly into individual serving bowls and ladle the hot soup over top!)

Adjust Seasoning & Serve: Taste and adjust salt and pepper if needed. Ladle generous steaming bowls of soup, top each with a generous handful of shredded sharp cheddar cheese and fresh chopped parsley, and serve with crusty sourdough bread!