Wash and scrub the potatoes well. Slice them into ¼-inch thick rounds. Try to keep them even so they cook at the same rate.

Place the sliced potatoes in a bowl of cold water and let them soak for 20–30 minutes. This removes excess starch and helps them crisp later.

Drain and pat completely dry with paper towels.

Heat 2 tablespoons olive oil and 2 tablespoons butter in a large skillet over medium-high heat.

Add the potatoes in a single layer (work in batches if needed). Let them cook undisturbed for several minutes until the bottoms turn golden brown. Flip and continue cooking until both sides are crisp and the centers are tender.

Remove potatoes to a plate and lightly season with salt and pepper.

In the same skillet, lower the heat to medium. Add the remaining butter and olive oil.

Add the sliced onions and a pinch of salt. Cook slowly, stirring often, for 15–20 minutes, until the onions are soft, golden, and lightly caramelized.

This step is where the magic happens. Don’t rush it.

Return the cooked potatoes to the skillet with the onions. Gently toss everything together so the potatoes soak up the buttery onion flavor.

Taste and adjust seasoning. Sprinkle with fresh parsley if using.

Serve immediately while hot and crispy.