Place potatoes in a large saucepan and cover with water; bring to a boil over medium-high heat. Cover and cook for 20-30 minutes or until tender.
In a small bowl, combine the mayonnaise, yogurt, vinegar, mustard, garlic and salt.
Peel warm potatoes and slice into a large bowl; add the bacon and onion. Pour dressing over potato mixture and gently toss to coat. Fold in apples. Cover and refrigerate for several hours before serving.