This recipe is also from my MIL. She uses it on a salad of broccoli, cauliflower, and onion. She also says it is good on cole slaw.

1 cup Miracle Whip
1/3 cup sugar
2 TBSP vinegar
1/4 tsp vinegar
1/2-1 teaspoon mustard seed

Add a tsp of Dijon mustard for potato salad.