10 lbs. potatoes
Salt
1 (32 oz.) jar mayonnaise
1/2 c. cider vinegar
2 tbsp. salt
1 tsp. pepper
1/2 c. finely chopped onion

About 8 hours ahead, cook peeled potatoes in boiling salted water for about 30 minutes or until tender. Meanwhile, combine mayonnaise with next 4 ingredients into a large bowl. Drain potatoes, peel, slice into bowl. Add onion and mayonnaise mixture; mix gently but well; chill well.