This is as good as anything you'll buy from the store or get from a restaurant

1/2 cup sugar free ketchup
1/2 cup oil
1/4 cup cider vinegar
1/3 cup. splenda or sweetner equal to 1/3 cup sugar
1/2 tsp. salt
1 tsp. yellow mustard
1 tsp. onion powder

Place all ingredients in a small bowl and whisk well. Store covered in refrigerator.