Heat the oven to 400 degrees and line a medium rimmed baking sheet with foil or parchment.
Prepare the adobo seasoning: In a small bowl, combine 1½ teaspoons salt with the garlic powder, oregano, turmeric and pepper, and mix well with a fork.
Put potatoes in a large bowl and randomly poke a few small holes in each with a fork. Pour in 2 tablespoons of the olive oil and toss potatoes well, then sprinkle with the adobo seasoning, and stir to combine. Pour in the remaining 1 tablespoon olive oil and toss a bit more to ensure the potatoes are evenly coated with spices.
Transfer potatoes to the lined baking sheet in an even layer, being careful not to crowd the pan.
Bake for 30 to 40 minutes, shaking the pan every 10 minutes or so. Potatoes are done when they pierce easily with a fork or the tip of a sharp knife. Taste and add more salt, if desired