Break up the beef. Add the raw ground beef and beef broth to a cold saucepan. Use a potato masher or whisk to break the beef into very fine pieces before turning on the heat.
Cook the beef. Set the pan over medium heat and bring to a simmer, mashing and stirring often, until no pink remains, 6 to 8 minutes. Skim off excess fat if desired.
Season. Stir in the onion, tomato sauce, tomato paste, chili powder, cumin, paprika, garlic powder, brown sugar, mustard, Worcestershire, salt, pepper and cayenne.
Simmer. Reduce heat to low and simmer uncovered for 20 to 25 minutes, stirring occasionally, until slightly thickened.
Thicken. Whisk the masa harina and water in a small bowl. Stir into the chili and simmer 2 to 3 minutes more, until it coats the back of a spoon.
Taste and serve. Adjust salt to taste. Spoon over hot dogs, tater tots, fries or burgers and top with cheddar and diced onion.