Brown the ground beef in a large skillet over medium heat until fully cooked. Drain excess grease.
Add the diced onion and garlic to the skillet and cook for 2 to 3 minutes until softened.
Transfer the beef mixture to the slow cooker.
Add the potatoes, carrots, green beans, diced tomatoes, beef broth, tomato paste, Worcestershire sauce, Italian seasoning, paprika, salt, and pepper.
Stir everything together until well combined.
Cover and cook on LOW for 7 to 8 hours or HIGH for 4 to 5 hours, until the vegetables are fork tender.
For a thicker stew, whisk the cornstarch and water together, stir into the slow cooker during the last 20 minutes of cooking, and cook until thickened.
Taste and adjust the seasoning before serving.