Heat water to boiling in a large, heavy saucepan. Add beans to water gradually so boiling will not stop. Simmer 2 minutes and remove saucepan from heat. Set beans aside to soak 1 hour.

Add salt to saucepan. Cover pan tightly and bring mixture to boiling over high heat. Reduce heat and simmer 2 hours or until beans are tender, stirring occasionally.

Heat oil in a large, heavy skillet over low heat. Add onion and garlic. Cook over medium heat until onion is transparent, occasionally moving with a spoon. Add the cooked beans, the cooking liquid, chili powder and pepper.

Mash the bean mixture in the skillet. Continue cooking over medium heat, stirring occasionally, until mixture is thick.