1 cup chopped onion
7 bacon strips, cooked and crumbled
2 tablespoons minced fresh parsley
1-1/3 cups mayonnaise
3 tablespoons grated Parmesan cheese
3 tablespoons prepared ranch salad dressing
2 tablespoons prepared mustard
4 teaspoons white vinegar
1/2 teaspoon minced garlic
1/4 teaspoon salt
1/4 teaspoon pepper
Place potatoes in a large saucepan and cover with water. Bring to a boil. Reduce heat; cover and cook for 10-15 minutes or until tender. Drain.
In a large bowl, combine the potatoes, onion, bacon and parsley. In a small bowl, combine the remaining ingredients. Pour over potato mixture; toss to coat. Refrigerate for 1 hour or until chilled.