The shack bbq sauce

1. Combine chili powder, pepper and salt.
2. In a large saucepan, combine ketchup, vinegar, water and onion and stir in dry mixture.
3. Bring to rolling boil, reduce heat and cook uncovered 1 ½ hours, stirring every 10 min. the mixture will reduce almost to half.
4. Pour into sterilized jars and let rest for a few days.