Heat the pot over medium-high heat. Add tomato paste and scrape the pan to ensure that the paste cooks evenly. Cook until paste begins to brown and emit a rich fragrance, approximately 1 to 3 minutes.
Remove pot from heat and add ground beef and water. Mix into a sludge. Return to heat and bring to a simmer, stirring into a paste. Add all ingredients except vinegar and chocolate.
Simmer gently based on preference. At minimum simmer for 1 hour, but you can go up to 3 hours. The flavor will become stronger as time progresses, so taste occasionally to find your favorite.
The next two steps are for 80:20 ground beef. If you want to skip these steps use lean ground beef instead.
OPTIONAL STEP 1: Cool, then refrigerate overnight in airtight container.
OPTIONAL STEP 2: Scrape solidified fat off surface of chili
Bring to a rapid simmer, then add vinegar and chocolate.