1. Combine sour cream and mayonnaise in small bowl.
2. Chop bacon and red onion and add to sour cream mixture.
3. Stir in salt and black pepper, cover and refrigerate.
4. Preheat oven to 425°.
5. Bake potatoes for 50-60 minutes or until tender.
6. Remove potatoes from oven and cool completely.
7. Coarsely chop potatoes into 1/2-inch pieces.
8. Place in large bowl and fold in sour cream mixture.
9. Sprinkle sliced green onions and shredded cheddar cheese over the top.
10. Cover and refrigerate 4-6 hours or overnight.