- 2tablespoons olive oil
- 1 medium red onion, chopped, plus more for serving
- 1 green bell pepper, chopped
- 2 cloves garlic, chopped
- 3/4pound ground beef chuck
- 2tablespoons tomato paste
- 2teaspoons chili powder
- 3/4teaspoon ground cumin
- kosher salt and black pepper
- 1 28-ounce can diced tomatoes
- 1 15-ounce can kidney beans, rinsed
- 1ounce semisweet chocolate, chopped
- 1tablespoon red wine vinegar
- sliced avocado, for serving
- Heat the oil in a large saucepan over medium-high heat. Add the onion, bell pepper, and garlic, and cook, stirring occasionally, until tender, 8 to 10 minutes.
- Add the beef and cook, breaking it up with a spoon, until no longer pink, 4 to 6 minutes. Add the tomato paste, chili powder, and cumin and cook, stirring, for 1 minute.
- Add the tomatoes (with their juices), beans, chocolate, ½ cup water, 1 teaspoon salt, and ¼ teaspoon pepper and bring to a boil. Reduce heat and simmer, stirring occasionally, until thickened, 20 to 25 minutes. Add the vinegar and stir to combine.
- Serve with the avocado and additional onion, if desired.