Rinse soup mix before using. Heat oil in a large soup pot over medium heat. Add onion and saute until soft, 7–10 minutes. Add garlic, chili powder and salt and saute until fragrant, about 1 minute. Add soup mix and water and bring to a boil. Reduce heat to a simmer and cook until the beans have just begun to soften, about 60 minutes.
Meanwhile, brown beef in a large saute pan; season to taste with salt and pepper. Add browned beef and tomato sauce to the beans and simmer for 1 hour. Adjust consistency with more water, if desired.