Brown hamburger and onion together. Drain grease. Mix in ketchup and taco seasoning.
Pour frozen shredded potatoes into crockpot. Add in meat mixture, sour cream, soup, Rotel, shredded cheese, and any other seasoning you like. I always do at least salt, pepper, onion, and garlic powder in everything. You can put everything on top of the potatoes and wait for it to cook for 30 minutes to an hour before mixing it together, otherwise you might make a mess.
Cook on high for 3 hours or until the potatoes are cooked. Stir every 30 minutes while cooking.