Heat oil in large pan over medium heat. Add onions, bell pepper, garlic, chili powder, cumin, coriander, pepper flakes, oregano, and cayenne; cook, stirring occasionally, until vegetables are softened and beginning to brown, about 10 minutes.
Increase heat to medium-high and add half the beef; cook, breaking up pieces with a wooden spoon, until no longer pink and just beginning to brown, 3 to 4 minutes. Add remaining beef and cook, breaking up pieces with a wooden spoon, until no longer pink, 3 to 4 minutes.
Pour all contents into crock pot.
Add beans, tomatoes, tomato puree, and 1/2 teaspoon salt into crockpot. Stir everything to combine.
Cook on low for 8-9 hours or high for 4-5 hours.