In a large pan, heat vegetable oil over medium heat. Add chopped onions, diced red bell pepper, and minced garlic. Stir in spices and cook for about 10 minutes, until softened.

Increase heat to medium-high and brown half of the ground beef. Transfer to a bowl and repeat with remaining beef.

Transfer the sautéed mixture into the slow cooker, scraping all flavorful bits from the pan.

Add kidney beans, pinto beans, diced tomatoes, and tomato puree to the slow cooker. Season with salt to taste and mix well.

Cover and cook on low for 8-9 hours or high for 4-5 hours until flavors meld.

Ladle into bowls and serve warm with toppings like shredded cheese and diced avocado.