Heat the olive oil in your Dutch oven over medium heat until shimmering. Add the chopped onion and cook, stirring occasionally, until translucent and fragrant, about 5 minutes.
Add the minced garlic and cook for another minute, until fragrant; avoid burning it to prevent bitterness.
Stir in the chopped roasted red bell pepper and cook for 2-3 minutes, allowing the flavors to meld and the peppers to soften slightly.
Add the ground beef, breaking it apart with your spoon, and cook until browned and no longer pink, about 8-10 minutes. Drain excess fat if necessary.
Sprinkle in the ground cumin, chili powder, and cocoa powder, stirring well to coat the meat evenly. Cook for 1-2 minutes until spices become fragrant.
Pour in the diced tomatoes along with their juices and add the drained kidney beans. Stir everything together, scraping up any browned bits from the bottom of the pot.
Bring the chili to a simmer, then reduce the heat to low. Cover partially and let it simmer gently for 45-60 minutes, stirring occasionally to prevent sticking and to deepen the flavors.
Uncover the pot and taste the chili, adjusting seasoning with salt and pepper as needed. Let it simmer uncovered for another 10 minutes for a thicker, richer consistency.
Once the chili is thick and aromatic, ladle it into bowls. Garnish with your favorite toppings like shredded cheese, chopped cilantro, or sour cream if desired.
