Wash the potatoes and place them in a pot with enough water to cover them.
Cook for about 30 minutes, until they are tender but not overcooked.
While the potatoes are boiling, peel the onion, cut it in half, and then slice it thinly.
Cut the bacon into slices and then into small cubes.
Once cooked, drain the potatoes and let them cool slightly.
Peel them, cut them in half, and then cut them into rough cubes.
In a skillet, heat the oil and half of the butter.
Add the onions and cook for a few minutes.
Add the bacon and cook until browned, about 10 minutes.
Add the potatoes to the skillet and mix well.
Use a spoon to gently smash some of the potatoes to create a variety of textures.
Season with salt and pepper to taste.
Add the remaining butter and continue cooking over medium-high heat for another 10–13 minutes.
Continue cooking until a golden crust forms on the bottom of the potatoes.
Serve the potatoes hot, straight from the skillet.