Brush the potatoes with some of the olive oil. Sprinkle with salt. Bake in the preheated oven for 1 hour, or until cooked through.
Once cool enough to handle, cut the potatoes in half lengthways. Scoop out the flesh, leaving a bit on the skins. Set the flesh aside for another use (great for soups, pie toppings or fish cakes). Cut the hollowed out halves in half again.
In a frying pan, melt the butter together with the olive oil. Add the salt and pepper. Once melted, brush this mixture on the potato skins. Return to the oven on a baking tray and bake for 12-15 minutes until golden. Let cool slightly before filling.
Sprinkle the salmon with lemon juice. Mix together the yoghurt, capers, dill and salmon. Spoon a dollop of this filling over each potato skin. Garnish with dill fronds and serve.
These are fantastic I made them for a party last night and guests couldn't get enough. they're extremely easy to make and you can easily do the first half of the recipe ahead of time. the Greek yogurt worked well but I think you could even try creme fraiche or cream cheese. Excellent! - 16 Dec 2011