In a ziplock bag, mix garlic powder and cumin together; add the cubed potatoes, seal the ziplock and toss it all together until potatoes are coated evenly.
In a large heavy skillet, over medium heat melt the oil and butter together.
Add the seasoned potatoes and cook, stirring frequently, until they're a nice golden brown, about 10 minutes; cover and cook an additional 10 minutes or until potatoes are tender, then season to taste with salt and pepper.
Transfer the sauted potatoes to a nonstick baking sheet and bake at 475 degrees for 10 minutes, stirring occasionally, until potatoes are nice and crisp.
When potatoes are almost done baking, place the cubed velveeta, salsa and tabasco in a microwave safe bowl and microwave for 1 minute; stir and microwave another minute; stir again and microwave for 1 more minute, then stir until smooth.
For each serving, place some potatoes in a bowl, then pour over 1/4 of the melted velveeta cheese sauce, top with some sour cream, then sprinkle with chopped green onion.