Cut the potatoes: Once the potatoes are washed and scrubbed well, cut into half-inch cubes.

Add the potatoes to a pot and cover with water: Add the cubed potatoes to a large saucepan and cover with cold water to about one inch above the potatoes. Add a pinch of salt.

Parboil the potatoes: With the saucepan uncovered, bring the water to a boil, then cook for an additional minute or two to parboil the potatoes.

Cook the onions: While the water comes to a boil, heat 1 tablespoon of olive oil in a skillet, over medium heat. When hot, add the onions, season with salt and pepper, and cook, stirring occasionally, until soft and fragrant, about 5 minutes.

Test the potatoes for doneness: To test the potatoes for doneness, stick the tip of a paring knife into a few of the potato cubes. The flesh should feel slightly firm, but softer and more tender than before cooking. The potatoes should not feel mushy.

Drain the potatoes: Drain the potatoes in a colander, shake off any excess water, and cool for about 5 minutes.

Heat oil and butter in a large skillet: Heat the remaining olive oil and butter in a wide cast iron pan or large skillet over medium heat.

Add potatoes, season, and cook: When the oil is hot and shimmering, add the potatoes, season with salt and pepper, and toss to coat with the oil. Spread the potatoes in a single layer across the bottom of the pan, working in batches if necessary. Cook the potatoes, without stirring, for 8 to 10 minutes, so the bottoms become nicely browned and crispy.

Add cooked onions and spices: Add cooked onions, garlic powder, and paprika to the skillet and stir to combine.

Serve immediately: Remove the pan from the heat and serve immediately.