Heat a Dutch oven or other large heavy-bottomed pot over medium heat. Add the oil, beef, bell peppers, yam, and celery, and cook until the meat is no longer pink and the vegetables are tender, about 5 minutes.
Add the chili powder, chipotle powder, oregano, salt and pepper. Mix well and cook for about 1 minute.
Stir in the tomato paste, diced tomatoes, and broth. Bring to a boil, then reduce the heat and simmer uncovered for about 30 minutes, until the chili reaches desired thickness (the longer it simmers, the thicker it will become)
Serve in bowls, and garnish with optional toppings if desired.