Peel and grate the potatoes into a large bowl of water. Keeping the shreds submerged prevents them from discoloring while you finish grating.
Transfer the potato to a large colander and rinse until the water runs clear. This removes loose starch from the surface.
Work by handfuls, squeezing firmly to remove excess water. Return the potato to the bowl.
Mix in 1 tablespoon of olive oil, the salt, and black pepper.
Heat 2 tablespoons of olive oil in a 22cm/9-inch nonstick pan over medium-high heat.
Spread the potato mixture into the pan and lightly pat it into an even round about 1.5cm/0.6 inch thick.
Cook for 5 to 8 minutes. Lift a corner with a spatula; the underside should be golden brown and crisp.
Slide the hash brown onto a large plate. Place the pan over the plate and quickly invert it, using a tea towel to protect your hands.
Drizzle the remaining tablespoon of oil around the pan edges. If the hash brown cracks, use a spatula to nudge it back together.
Cook for 4 to 6 minutes, lifting a corner to check the second side.
Slide it onto a serving plate, taste for seasoning, and cut into wedges.