Heat olive oil on medium-high heat in a heavy-bottomed pot. I like to use an enamel-coated cast iron pot. Add diced onion and sauté for 3-5 minutes, just until tender.
Add ground beef and cook over medium heat, breaking up the beef. Cook until nearly browned but not all the way cooked through.
Add garlic and cook for 2 minutes until fragrant.
Add in all bell peppers, chili powder, cumin, and oregano. Stir to combine and cook for 5 minutes, occasionally stirring
Lastly, add tomato paste, crushed tomatoes, and broth. Bring to a simmer, cover, and turn to low heat.
Simmer for 2-3 hours while stirring occasionally.