Prep the oven: set to the ‘warm’ setting or heat to low or around 75-90°C or 170-195°F, depending on your oven. Prep an oven tray: brush it with olive oil and have some foil ready to cover it completely.
Fry the bacon: to a large frying pan or round flat-bottomed wok over medium heat, add a tablespoon of olive oil, heat, and fry the diced bacon until cooked to your liking. Transfer to the oven tray.
Fry the mushrooms: to the same pan or wok over medium, heat another tablespoon of olive oil and the butter, add the mushroom slices, stir so they’re coated both sides in oil and butter, leave the mushrooms alone until they release then reabsorb their liquid and brown, around 5 minutes or so.
Use a spatula to turn the mushrooms to brown the other side, for another few minutes or so. Give them a gentle stir, then transfer the mushrooms to the tray with the bacon. Depending on the size of your wok/pan, you may have to do the mushrooms in two batches. As cooked, transfer them to the oven tray to keep warm. When done, wipe the pan or wok with a paper kitchen towel.
Cook the potatoes: add 2 tablespoons olive oil to the pan (or wok), heat, add the diced potatoes, use the spatula or tongs to turn the potatoes so they’re completely coated with oil, then leave them to cook over medium heat for five minutes or so to let them start to colour until golden-brown.
Turn the potatoes then leave them for another five minutes or so to colour. Repeat until the potatoes are cooked through, golden brown on all sides, and crispy and dark-brown on the edges, around 10-15 minutes or so. If the potatoes stick to the pan, scrape those stuck bits off; they’ll brown and crisp up and add crunchy texture to the dish.
Combine the lot: when the potatoes are done and are tender-soft inside and golden-brown and crispy on the outside, slide the tray out of the oven, add the potatoes to the mushrooms and bacon, use a spatula or spoon to gently combine the lot, cover with foil and slide the tray back into the oven until ready to serve.
Season and garnish: when you’re ready to serve, grind on some freshly ground black pepper, sprinkle on the optional salt (if your doctor hasn’t told you you’re a walking time bomb and don’t have hypertension, as I do), shower with half the chopped parsley (and/or dill), fold in gently, and scatter a little more parsley on top.
Serve: distribute between bowls and eat the potatoes on their own in your pyjamas on the sofa — or serve as a hearty, comforting side dish to roast chicken, juicy sausages, or a great steak.
Serve with dishes of dill pickles to provide a tangy-sour contrast, wholegrain mustard for some zing and pop, sour cream for dolloping on top, and more finely chopped fresh parsley or fresh dill, so guests can adjust to their liking.