Bake sweet potato for 1 hour and 10 minutes in a 350-degree oven or microwave sweet potato for 8-9 minutes. Cool, peel, and dice potato into 1/2 inch pieces.
Saute the onions in oil (or use a non-stick pan) until soft, about 5-10 minutes. For a richer flavor, caramelize onions by cooking an additional 10 minutes and stirring every minute so that they brown but do not burn. Add garlic and cook over medium heat for 2 minutes. Deglaze with water if onions and garlic start to get too brown.
Add the remaining ingredients and bring up the heat to just below boiling. Reduce the heat to low and let simmer for two hours; OR place in a 350-degree oven with a cover on the pot and cook the chili for 1.5 hours on high.
Instant Pot - skip the sautéing of the onion and garlic and instead combine all ingredients into an Instant Pot and cook on the "pressure cook" setting for 8 minutes. Release the steam valve. When the float button depresses, you can remove the lid.