Saute the diced onion in the oil until soft, about 5-7 minutes.
Add the ground beef and cook until browned, about 5-7 minutes.
Add in the tomatoes and chili seasoning.
Stir to combine. The mixture should be thick.
Pour in the 3 cans of beans, undrained.
If you like hot sauce, add it here.
Stir well and cook over medium-high heat until the chili boils.
Once boiling, reduce heat to low, cover, and let simmer for 30 minutes.
Stir occasionally in order to prevent burning on the bottom of the pan.
Serve warm topped with cheddar cheese or sour cream.
In the Crockpot:
Cook as the onion and ground beef as directed above and move to the Crockpot.
Add in all the other ingredients and stir.
Cook on LOW for 6 hours.
Let chili cool before packaging.
Package in gallon ziplock bags or airtight containers.
To thaw, let it sit in your refrigerator overnight or run warm water over the ziplock.
Heat in a large pan until warm and bubbling.