First, wash and dry the Yukon potatoes. You'll want to dice them with the skin on into small cubes. Also, dice the onion.
Toss the potatoes in salt and pepper but don't over do it because you can add more later.
In a skillet on medium heat add the vegetable oil. Just enough to cover the bottom. Add in only the diced potatoes. The potatoes should sizzle. Test with a piece or two before adding all of them.
Spread them out in the pan and allow them to cook. Do not turn them too much. Allow them to sauté a while then turn them.
Once at least 2 sides are golden brown with the potatoes add in the diced onion. Continue cooking allow the onions to brown as well. If the potatoes are still hard, this is where you may need to add a lid for about 5 minutes to help them soften.
Now, right before the potatoes are finished add in butter, dried thyme and the garlic powder. Cook the potatoes about 1-2 minutes longer then turn off the heat and add them to a paper towel to drain a bit.
Allow them to cool then serve.