Heat a large heavy-bottomed pot or Dutch oven over medium-high heat. Add 1 tablespoon oil. When shimmering, add diced yellow onion and green bell pepper. Sauté until onion is translucent and pepper has softened, about 5 minutes. Add minced garlic and cook, stirring, 30–45 seconds until fragrant.

Brown the beef

Push vegetables to the side and add the ground beef to the pot. Break up with a wooden spoon and brown until no longer pink and some browned bits form, about 6–8 minutes. Drain excess fat if desired, leaving enough to coat the pan (~1 tsp) for flavor.

Tomato base

Stir in 3 tablespoons tomato paste and cook 2 minutes, stirring, to caramelize slightly. Add the canned diced tomatoes and 2 cups beef broth; scrape up any browned bits from the bottom of the pot.

Add beans

Stir in the drained kidney beans and pinto beans so they are evenly distributed through the mixture.

Seasoning & Spice Blend

Add spices

In a small bowl combine chili powder, ground cumin, paprika, dried oregano, dark brown sugar, unsweetened cocoa powder (if using), ground black pepper, kosher salt, and red pepper flakes. Add the spice blend to the pot and stir thoroughly so the spices dissolve into the liquid and coat the meat and beans.

Bring the chili to a gentle simmer over medium heat. Once simmering, reduce heat to low, partially cover the pot, and simmer gently for 35–45 minutes, stirring occasionally, until flavors meld and chili thickens. If the chili becomes too thick, add up to 1/2 cup additional beef broth or water to reach desired consistency.

Finishes & Garnishes

Finish and balance

After simmering, remove from heat and stir in 1 tablespoon apple cider vinegar and 1 tablespoon Worcestershire sauce to brighten and deepen flavor. Taste and adjust seasoning with additional salt, pepper, or a pinch more sugar if needed.

Rest

Let the chili rest 5–10 minutes off the heat to allow flavors to settle and it to thicken slightly before serving.

Serve

Ladle chili into cups or bowls. For cup-size portions, add shredded cheddar and diced raw onion as optional add-ons. For bowl-size portions, increase cheddar and onion amounts as desired. Garnish with chopped cilantro if using. Serve with crackers or cornbread if desired.