Walla Onion Potato Salad

3 pounds red new potatoes -- skinned
1 large Walla Walla, Vidalia or other mild onion
1 cup sliced celery
1 large Golden delicious apple -- diced
20 large pimiento stuffed olives -- sliced
1/3 cup sweet pickle relish
1 1/2 cups mayonnaise
2 teaspoons Dijon mustard
2 tablespoons white wine vinegar
2 tablespoons steak sauce
salt and pepper -- to taste

Boil potatoes until just tender when pierced by a fork. Drain, let cool and dice into a large bowl.

Cut onions into quarters and slice thin; add to potatoes along with celery, apples, olives and pickle.

In a small bowl, stir mayonnaise, mustard, vinegar and steak sauce. Spoon over potato mixture and mix gently.

Season with salt and pepper. Cover and refrigerate for at least 2 hours or until the next day.