Claudeens's Broccoli salad

I've seen this salad many times and made many different ways but this is my Aunt Claudeens way.

2 stalks broccoli floretes
1 cup raisins
small red or sweet onion(about 1/2 cup)
10-12 slices bacon

Dressing
1 cup mayonnaise
2 Tbsp white vinegar

Marinade for at least 2 hours.