Ideal Slow Cooker Size: 5 to 6-quart.Put the ground beef and onions in a large nonstick skillet set over medium heat. Season with salt, pepper and additional seasoning if you like. Cook, stirring and breaking up the beef into small crumbles, until the ground beef is no longer pink and the onions have softened, 5 to 7 minutes.Drain off any excess fat. (There shouldn't be much if you used extra lean ground beef.) Scrape the ground beef mixture into the crock pot. Add the potatoes, mixed vegetables, corn, diced tomatoes, tomato sauce, beef broth and water. Cover and cook on LOW 6 to 8 hours or until the vegetables are all tender. The potatoes will take the longest to soften, so be sure to chop them really small if time is an issue for you.Taste and add additional salt and pepper, if desired.