My Grandmother's Salad Dressing

4 slices bacon
1/2 cup onions, minced (optional)
1 tablespoon sugar
1 teaspoon salt
1/2 teaspoon pepper
1/2 teaspoon celery seed
1/3 cup water
1/4 cup vinegar
parsely, minced
 
 
This is my Grandmother's dressing for German Potato Salad, but I use it for Wilted lettuce also.  I think she did too.  This recipe was not written anywhere until I got married and asked her to write out some of my favorite recipes of hers. So, the amounts were guess-timates.