Grate potatoes using the large holes of a box grater.
Using a clean dish towel or cheese cloth, drain potatoes completely, removing as much water as possible.
Transfer potatoes to a large bowl. Stir in garlic powder and onion powder; season with salt and pepper, to taste.
Heat 2 tablespoons canola oil in a large cast iron skillet over medium heat.
Working in batches, spread potatoes in a single layer and cook, undisturbed, until golden brown, about 5-6 minutes. Flip and cook on the other side until evenly golden and crispy, about 3-4 minutes longer. Repeat with remaining canola oil and potatoes.
Serve immediately.
