Line a baking tray with parchment paper and set aside.
Heat a large pot filled with water on high heat.
Peel potatoes and cut into thirds. Add to the boiling water and cook for 10 minutes.
Meanwhile, prepare an ice bath by filling a large bowl with ice and topping up with water.
After 10 minutes, add potatoes to the water bath for 3-4 minutes to cool. Drain.
Grate potatoes. Add to a large bowl.
To a large bowl, add grated potatoes, egg, cornstarch, salt, and pepper. Mix until fully combined
Evenly divide the potato mixture and form patties. and place on parchment lined baking tray. Place hashbrown patties in the freezer for 30 minutes.
In a large skillet on medium high heat, heat oil until hot. Place hashbrown in the hot oil and fry until golden brown on both sides (about 4-5 minutes per side).
Remove from oil and drain on a paper towel. Sprinkle with salt and serve.
Notes
Leftover hashbrowns will keep in a covered container in the refrigerator for 4 days.