1 1/2 lb small potatoes, boiled in their skins, peel, then place the potatoes in the fridge overnight)
1 medium onion, finely chopped
4 thin slices of bacon or speck, cut into small cubes
2-3 tbsps of olive oil & butter (50/50)
Salt and black pepper to season
Slice the cold potatoes into thin 1/8" slices, then set aside.
Add about 1 tbsp of the oil to a large frying pan and heat gently. Fry the onions till soft then add the bacon pieces. Continue frying till the bacon and onions are lightly browned then remove from the pan with a slotted spoon. Set aside for now.
Add the remaining oil and butter to the pan and fry the potato slices over a low/medium heat, turning them occasionally. Allow them to brown lightly on one side before turning, repeating the process till most of the potatoes are golden brown. Once the potatoes are almost done, return the onion and bacon mix to the pan, season with salt and plenty of black pepper, then continue frying over a medium heat till everything is nicely browned.