For the stovetop: Heat a large soup pot or Dutch oven over medium-high heat then add ground beef and onion and saute until cooked through, breaking beef up as it cooks. Add remaining ingredients, except toppings, then turn heat up to high to bring to a boil. Place a lid on top then turn the heat down to medium-low and simmer for 30 minutes, stirring occasionally. Taste then add more taco seasoning if desired, and then serve with toppings.
For the Crock Pot: Heat a large skillet over medium-high heat then add ground beef and onion and saute until cooked through, breaking beef up as it cooks. Drain if necessary then add mixture to a 6 quart crock pot with the remaining ingredients, except toppings, and stir to combine. Cook on low for 4-6 hours then serve with toppings.