Preheat a large pot or dutch oven over medium-high heat. Add oil or butter. Add ground beef, season with half of the salt and all of the pepper, and cook until well-browned, about 3-5 minutes. Transfer meat to a paper towel lined plate to drain.

Reduce heat to low and add onions. Season with the rest of the salt. Cook until onions have softened, about 2-3 minutes. Add garlic and cook for one minute more.

Add beef broth, diced tomatoes, tomato sauce, pinto and kidney beans, chili powder, cumin and brown sugar. Add the browned beef back into the pot along with the remaining salt.

Bring to a boil and simmer for at least about 20 minutes, until thickened. Add more salt to taste if needed. If you have more time, keep simmering on low heat (up to no more than 4 hours total) and stir occasionally.

Serve with desired toppings and store any leftovers in the refrigerator.