Brown the beef and onion in large stock pot (or saucepan if you’re planning to be it all in a crock pot).
Add the remaining ingredients and simmer for at least 1 hour, or until ready to serve. (Drain the corn, but not the tomatoes.)
CROCKPOT: Add the browned beef and onion, then the rest of the ingredients. Cook on low for 6 hours.
Serve with grated cheese, sour cream, chopped green onions, diced tomatoes, cilantro, lime, and crushed tortilla chips or tortilla strips. You can also serve inside individual Frito bags for walking tacos.