For the filling

1. In a large bowl, mash up the tuna with a fork.
2. Add mayonnaise, sour cream, black pepper and green onions.
3. Keep in a covered container and keep it cool in the fridge.

For the baked potato

1. Pre-heat the oven to 170°C. Rub the potatoes with olive oil, sprinkle them with salt and pepper and prick them all over with a fork.
2. Place them on a baking sheet and cook potatoes for 30 to 60 minutes, until their skin is crispy and sticking one with a fork meets no resistance.
3. Once the potatoes are done, remove it from the oven and let it cool down a bit, for about 5 minutes.
4. Cut the potatoes into quarters but only 3/4 way through.
5. Place 1 to 2 tablespoon of tuna filling.
6. Top with some cheese and freshly cracked pepper.